PERLDIAG(1)

NAME
perldiag - various Perl diagnostics

DESCRIPTION
These messages are classified as follows (listed in increasing order of desperation):

    (W) A warning (optional).
    (D) A deprecation (optional).
    (S) A severe warning (mandatory).
    (F) A fatal error (trappable).
    (P) An internal error you should never see (trappable).
    (X) A very fatal error (nontrappable).
    (A) An alien error message (not generated by Perl).
Optional warnings are enabled by using the -w switch. Warnings may be captured by setting $SIG{__WARN__} to a reference to a routine that will be called on each warning instead of printing it. See the perlvar manpage. Trappable errors may be trapped using the eval operator. See the eval entry in the perlfunc manpage.

Some of these messages are generic. Spots that vary are denoted with a %s, just as in a printf format. Note that some messages start with a %s! The symbols "%(-?@ sort before the letters, while [ and \ sort after.

    (F) Lexically scoped variables aren't in a package, so it doesn't make sense to try to declare one with a package qualifier on the front. Use local() if you want to localize a package variable.

    (W) A lexical variable has been redeclared in the same scope, effectively eliminating all access to the previous instance. This is almost always a typographical error. Note that the earlier variable will still exist until the end of the scope or until all closure referents to it are destroyed.

    (F) The "no" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage.

    (F) The "use" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage.

% may only be used in unpack
    (F) You can't pack a string by supplying a checksum, because the checksumming process loses information, and you can't go the other way. See the unpack entry in the perlfunc manpage.

%s (...) interpreted as function
    (W) You've run afoul of the rule that says that any list operator followed by parentheses turns into a function, with all the list operators arguments found inside the parentheses. See the section on Terms and List Operators (Leftward) in the perlop manpage.

%s argument is not a HASH element
    (F) The argument to exists() must be a hash element, such as

        $foo{$bar}
        $ref->[12]->{"susie"}

%s argument is not a HASH element or slice
    (F) The argument to delete() must be either a hash element, such as

        $foo{$bar}
        $ref->[12]->{"susie"}
    or a hash slice, such as

        @foo{$bar, $baz, $xyzzy}
        @{$ref->[12]}{"susie", "queue"}

%s did not return a true value
    (F) A required (or used) file must return a true value to indicate that it compiled correctly and ran its initialization code correctly. It's traditional to end such a file with a "1;", though any true value would do. See the require entry in the perlfunc manpage.

%s found where operator expected
    (S) The Perl lexer knows whether to expect a term or an operator. If it sees what it knows to be a term when it was expecting to see an operator, it gives you this warning. Usually it indicates that an operator or delimiter was omitted, such as a semicolon.

%s had compilation errors
    (F) The final summary message when a perl -c fails.

%s has too many errors
    (F) The parser has given up trying to parse the program after 10 errors. Further error messages would likely be uninformative.

%s matches null string many times
    (W) The pattern you've specified would be an infinite loop if the regular expression engine didn't specifically check for that. See the perlre manpage.

%s never introduced
    (S) The symbol in question was declared but somehow went out of scope before it could possibly have been used.

%s syntax OK
    (F) The final summary message when a perl -c succeeds.

%s: Command not found
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: Expression syntax
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: Undefined variable
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

%s: not found
    (A) You've accidentally run your script through the Bourne shell instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

(Missing semicolon on previous line?)
    (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Don't automatically put a semicolon on the previous line just because you saw this message.

-P not allowed for setuid/setgid script
    (F) The script would have to be opened by the C preprocessor by name, which provides a race condition that breaks security.

-T and -B not implemented on filehandles
    (F) Perl can't peek at the stdio buffer of filehandles when it doesn't know about your kind of stdio. You'll have to use a filename instead.

-p destination: %s
    (F) An error occurred during the implicit output invoked by the -p command-line switch. (This output goes to STDOUT unless you've redirected it with select().)

500 Server error
    See Server error.

?+* follows nothing in regexp
    (F) You started a regular expression with a quantifier. Backslash it if you meant it literally. See the perlre manpage.

@ outside of string
    (F) You had a pack template that specified an absolute position outside the string being unpacked. See the pack entry in the perlfunc manpage.

accept() on closed fd
    (W) You tried to do an accept on a closed socket. Did you forget to check the return value of your socket() call? See the accept entry in the perlfunc manpage.

Allocation too large: %lx
    (X) You can't allocate more than 64K on an MS-DOS machine.

Applying %s to %s will act on scalar(%s)
    (W) The pattern match (//), substitution (s///), and transliteration (tr///) operators work on scalar values. If you apply one of them to an array or a hash, it will convert the array or hash to a scalar value -- the length of an array, or the population info of a hash -- and then work on that scalar value. This is probably not what you meant to do. See the grep entry in the perlfunc manpage and the map entry in the perlfunc manpage for alternatives.

Arg too short for msgsnd
    (F) msgsnd() requires a string at least as long as sizeof(long).

Ambiguous use of %s resolved as %s
    (W)(S) You said something that may not be interpreted the way you thought. Normally it's pretty easy to disambiguate it by supplying a missing quote, operator, parenthesis pair or declaration.

Ambiguous call resolved as CORE::%s(), qualify as such or use &
    (W) A subroutine you have declared has the same name as a Perl keyword, and you have used the name without qualification for calling one or the other. Perl decided to call the builtin because the subroutine is not imported.

    To force interpretation as a subroutine call, either put an ampersand before the subroutine name, or qualify the name with its package. Alternatively, you can import the subroutine (or pretend that it's imported with the use subs pragma).

    To silently interpret it as the Perl operator, use the CORE:: prefix on the operator (e.g. CORE::log($x)) or by declaring the subroutine to be an object method (see the attrs manpage).

Args must match #! line
    (F) The setuid emulator requires that the arguments Perl was invoked with match the arguments specified on the #! line. Since some systems impose a one-argument limit on the #! line, try combining switches; for example, turn -w -U into -wU.

Argument
    (W) The indicated string was fed as an argument to an operator that expected a numeric value instead. If you're fortunate the message will identify which operator was so unfortunate.

Array @%s missing the @ in argument %d of %s()
    (D) Really old Perl let you omit the @ on array names in some spots. This is now heavily deprecated.

assertion botched: %s
    (P) The malloc package that comes with Perl had an internal failure.

Assertion failed: file
    (P) A general assertion failed. The file in question must be examined.

Assignment to both a list and a scalar
    (F) If you assign to a conditional operator, the 2nd and 3rd arguments must either both be scalars or both be lists. Otherwise Perl won't know which context to supply to the right side.

Attempt to free non-arena SV: 0x%lx
    (P) All SV objects are supposed to be allocated from arenas that will be garbage collected on exit. An SV was discovered to be outside any of those arenas.

Attempt to free nonexistent shared string
    (P) Perl maintains a reference counted internal table of strings to optimize the storage and access of hash keys and other strings. This indicates someone tried to decrement the reference count of a string that can no longer be found in the table.

Attempt to free temp prematurely
    (W) Mortalized values are supposed to be freed by the free_tmps() routine. This indicates that something else is freeing the SV before the free_tmps() routine gets a chance, which means that the free_tmps() routine will be freeing an unreferenced scalar when it does try to free it.

Attempt to free unreferenced glob pointers
    (P) The reference counts got screwed up on symbol aliases.

Attempt to free unreferenced scalar
    (W) Perl went to decrement the reference count of a scalar to see if it would go to 0, and discovered that it had already gone to 0 earlier, and should have been freed, and in fact, probably was freed. This could indicate that SvREFCNT_dec() was called too many times, or that SvREFCNT_inc() was called too few times, or that the SV was mortalized when it shouldn't have been, or that memory has been corrupted.

Attempt to pack pointer to temporary value
    (W) You tried to pass a temporary value (like the result of a function, or a computed expression) to the "p" pack() template. This means the result contains a pointer to a location that could become invalid anytime, even before the end of the current statement. Use literals or global values as arguments to the "p" pack() template to avoid this warning.

Attempt to use reference as lvalue in substr
    (W) You supplied a reference as the first argument to substr() used as an lvalue, which is pretty strange. Perhaps you forgot to dereference it first. See the substr entry in the perlfunc manpage.

Bad arg length for %s, is %d, should be %d
    (F) You passed a buffer of the wrong size to one of msgctl(), semctl() or shmctl(). In C parlance, the correct sizes are, respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *), and sizeof(struct shmid_ds *).

Bad filehandle: %s
    (F) A symbol was passed to something wanting a filehandle, but the symbol has no filehandle associated with it. Perhaps you didn't do an open(), or did it in another package.

Bad free() ignored
    (S) An internal routine called free() on something that had never been malloc()ed in the first place. Mandatory, but can be disabled by setting environment variable PERL_BADFREE to 1.

    This message can be quite often seen with DB_File on systems with "hard" dynamic linking, like AIX and OS/2. It is a bug of Berkeley DB which is left unnoticed if DB uses forgiving system malloc().

Bad hash
    (P) One of the internal hash routines was passed a null HV pointer.

Bad index while coercing array into hash
    (F) The index looked up in the hash found as the 0'th element of a pseudo-hash is not legal. Index values must be at 1 or greater. See the perlref manpage.

Bad name after %s::
    (F) You started to name a symbol by using a package prefix, and then didn't finish the symbol. In particular, you can't interpolate outside of quotes, so

        $var = 'myvar';
        $sym = mypack::$var;
    is not the same as

        $var = 'myvar';
        $sym = "mypack::$var";

Bad symbol for array
    (P) An internal request asked to add an array entry to something that wasn't a symbol table entry.

Bad symbol for filehandle
    (P) An internal request asked to add a filehandle entry to something that wasn't a symbol table entry.

Bad symbol for hash
    (P) An internal request asked to add a hash entry to something that wasn't a symbol table entry.

Badly placed ()'s
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

Bareword
    (F) With "strict subs" in use, a bareword is only allowed as a subroutine identifier, in curly braces or to the left of the "=>" symbol. Perhaps you need to predeclare a subroutine?

Bareword
    (W) You used a qualified bareword of the form Foo::, but the compiler saw no other uses of that namespace before that point. Perhaps you need to predeclare a package?

BEGIN failed--compilation aborted
    (F) An untrapped exception was raised while executing a BEGIN subroutine. Compilation stops immediately and the interpreter is exited.

BEGIN not safe after errors--compilation aborted
    (F) Perl found a BEGIN {} subroutine (or a use directive, which implies a BEGIN {}) after one or more compilation errors had already occurred. Since the intended environment for the BEGIN {} could not be guaranteed (due to the errors), and since subsequent code likely depends on its correct operation, Perl just gave up.

bind() on closed fd
    (W) You tried to do a bind on a closed socket. Did you forget to check the return value of your socket() call? See the bind entry in the perlfunc manpage.

Bizarre copy of %s in %s
    (P) Perl detected an attempt to copy an internal value that is not copiable.

Callback called exit
    (F) A subroutine invoked from an external package via perl_call_sv() exited by calling exit.

Can't
    (F) A "goto" statement was executed to jump out of what might look like a block, except that it isn't a proper block. This usually occurs if you tried to jump out of a sort() block or subroutine, which is a no-no. See the goto entry in the perlfunc manpage.

Can't
    (F) A "goto" statement was executed to jump into the middle of a foreach loop. You can't get there from here. See the goto entry in the perlfunc manpage.

Can't
    (F) A "last" statement was executed to break out of the current block, except that there's this itty bitty problem called there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the last entry in the perlfunc manpage.

Can't
    (F) A "next" statement was executed to reiterate the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the next entry in the perlfunc manpage.

Can't
    (F) A "redo" statement was executed to restart the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block, as doesn't a block given to sort(). You can usually double the curlies to get the same effect though, because the inner curlies will be considered a block that loops once. See the redo entry in the perlfunc manpage.

Can't bless non-reference value
    (F) Only hard references may be blessed. This is how Perl "enforces" encapsulation of objects. See the perlobj manpage.

Can't break at that line
    (S) A warning intended to only be printed while running within the debugger, indicating the line number specified wasn't the location of a statement that could be stopped at.

Can't call method
    (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't have ANYTHING defined in it, let alone methods. See the perlobj manpage.

Can't call method
    (F) A method call must know in what package it's supposed to run. It ordinarily finds this out from the object reference you supply, but you didn't supply an object reference in this case. A reference isn't an object reference until it has been blessed. See the perlobj manpage.

Can't call method
    (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an expression that returns a defined value which is neither an object reference nor a package name. Something like this will reproduce the error:

        $BADREF = 42;
        process $BADREF 1,2,3;
        $BADREF->process(1,2,3);

Can't call method
    (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an undefined value. Something like this will reproduce the error:

        $BADREF = undef;
        process $BADREF 1,2,3;
        $BADREF->process(1,2,3);

Can't chdir to %s
    (F) You called perl -x/foo/bar, but /foo/bar is not a directory that you can chdir to, possibly because it doesn't exist.

Can't coerce %s to integer in %s
    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are. So you can't say things like:

        *foo += 1;
    You CAN say

        $foo = *foo;
        $foo += 1;
    but then $foo no longer contains a glob.

Can't coerce %s to number in %s
    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are.

Can't coerce %s to string in %s
    (F) Certain types of SVs, in particular real symbol table entries (typeglobs), can't be forced to stop being what they are.

Can't coerce array into hash
    (F) You used an array where a hash was expected, but the array has no information on how to map from keys to array indices. You can do that only with arrays that have a hash reference at index 0.

Can't create pipe mailbox
    (P) An error peculiar to VMS. The process is suffering from exhausted quotas or other plumbing problems.

Can't declare %s in my
    (F) Only scalar, array, and hash variables may be declared as lexical variables. They must have ordinary identifiers as names.

Can't do inplace edit on %s: %s
    (S) The creation of the new file failed for the indicated reason.

Can't do inplace edit without backup
    (F) You're on a system such as MS-DOS that gets confused if you try reading from a deleted (but still opened) file. You have to say -i.bak, or some such.

Can't do inplace edit: %s > 14 characters
    (S) There isn't enough room in the filename to make a backup name for the file.

Can't do inplace edit: %s is not a regular file
    (S) You tried to use the -i switch on a special file, such as a file in /dev, or a FIFO. The file was ignored.

Can't do setegid!
    (P) The setegid() call failed for some reason in the setuid emulator of suidperl.

Can't do seteuid!
    (P) The setuid emulator of suidperl failed for some reason.

Can't do setuid
    (F) This typically means that ordinary perl tried to exec suidperl to do setuid emulation, but couldn't exec it. It looks for a name of the form sperl5.000 in the same directory that the perl executable resides under the name perl5.000, typically /usr/local/bin on Unix machines. If the file is there, check the execute permissions. If it isn't, ask your sysadmin why he and/or she removed it.

Can't do waitpid with flags
    (F) This machine doesn't have either waitpid() or wait4(), so only waitpid() without flags is emulated.

Can't do {n,m} with n > m
    (F) Minima must be less than or equal to maxima. If you really want your regexp to match something 0 times, just put {0}. See the perlre manpage.

Can't emulate -%s on #! line
    (F) The #! line specifies a switch that doesn't make sense at this point. For example, it'd be kind of silly to put a -x on the #! line.

Can't exec
    (W) An system(), exec(), or piped open call could not execute the named program for the indicated reason. Typical reasons include: the permissions were wrong on the file, the file wasn't found in $ENV{PATH}, the executable in question was compiled for another architecture, or the #! line in a script points to an interpreter that can't be run for similar reasons. (Or maybe your system doesn't support #! at all.)

Can't exec %s
    (F) Perl was trying to execute the indicated program for you because that's what the #! line said. If that's not what you wanted, you may need to mention "perl" on the #! line somewhere.

Can't execute %s
    (F) You used the -S switch, but the copies of the script to execute found in the PATH did not have correct permissions.

Can't find %s on PATH, '.' not in PATH
    (F) You used the -S switch, but the script to execute could not be found in the PATH, or at least not with the correct permissions. The script exists in the current directory, but PATH prohibits running it.

Can't find %s on PATH
    (F) You used the -S switch, but the script to execute could not be found in the PATH.

Can't find label %s
    (F) You said to goto a label that isn't mentioned anywhere that it's possible for us to go to. See the goto entry in the perlfunc manpage.

Can't find string terminator %s anywhere before EOF
    (F) Perl strings can stretch over multiple lines. This message means that the closing delimiter was omitted. Because bracketed quotes count nesting levels, the following is missing its final parenthesis:

        print q(The character '(' starts a side comment.);
    If you're getting this error from a here-document, you may have included unseen whitespace before or after your closing tag. A good programmer's editor will have a way to help you find these characters.

Can't fork
    (F) A fatal error occurred while trying to fork while opening a pipeline.

Can't get filespec - stale stat buffer?
    (S) A warning peculiar to VMS. This arises because of the difference between access checks under VMS and under the Unix model Perl assumes. Under VMS, access checks are done by filename, rather than by bits in the stat buffer, so that ACLs and other protections can be taken into account. Unfortunately, Perl assumes that the stat buffer contains all the necessary information, and passes it, instead of the filespec, to the access checking routine. It will try to retrieve the filespec using the device name and FID present in the stat buffer, but this works only if you haven't made a subsequent call to the CRTL stat() routine, because the device name is overwritten with each call. If this warning appears, the name lookup failed, and the access checking routine gave up and returned FALSE, just to be conservative. (Note: The access checking routine knows about the Perl stat operator and file tests, so you shouldn't ever see this warning in response to a Perl command; it arises only if some internal code takes stat buffers lightly.)

Can't get pipe mailbox device name
    (P) An error peculiar to VMS. After creating a mailbox to act as a pipe, Perl can't retrieve its name for later use.

Can't get SYSGEN parameter value for MAXBUF
    (P) An error peculiar to VMS. Perl asked $GETSYI how big you want your mailbox buffers to be, and didn't get an answer.

Can't goto subroutine outside a subroutine
    (F) The deeply magical "goto subroutine" call can only replace one subroutine call for another. It can't manufacture one out of whole cloth. In general you should be calling it out of only an AUTOLOAD routine anyway. See the goto entry in the perlfunc manpage.

Can't goto subroutine from an eval-string
    (F) The "goto subroutine" call can't be used to jump out of an eval "string". (You can use it to jump out of an eval {BLOCK}, but you probably don't want to.)

Can't localize through a reference
    (F) You said something like local $$ref, which Perl can't currently handle, because when it goes to restore the old value of whatever $ref pointed to after the scope of the local() is finished, it can't be sure that $ref will still be a reference.

Can't localize lexical variable %s
    (F) You used local on a variable name that was previously declared as a lexical variable using "my". This is not allowed. If you want to localize a package variable of the same name, qualify it with the package name.

Can't localize pseudo-hash element
    (F) You said something like local $ar->{'key'}, where $ar is a reference to a pseudo-hash. That hasn't been implemented yet, but you can get a similar effect by localizing the corresponding array element directly -- local $ar->[$ar->[0]{'key'}].

Can't locate auto/%s.al in @INC
    (F) A function (or method) was called in a package which allows autoload, but there is no function to autoload. Most probable causes are a misprint in a function/method name or a failure to AutoSplit the file, say, by doing make install.

Can't locate %s in @INC
    (F) You said to do (or require, or use) a file that couldn't be found in any of the libraries mentioned in @INC. Perhaps you need to set the PERL5LIB or PERL5OPT environment variable to say where the extra library is, or maybe the script needs to add the library name to @INC. Or maybe you just misspelled the name of the file. See the require entry in the perlfunc manpage.

Can't locate object method
    (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't define that particular method, nor does any of its base classes. See the perlobj manpage.

Can't locate package %s for @%s::ISA
    (W) The @ISA array contained the name of another package that doesn't seem to exist.

Can't make list assignment to \%ENV on this system
    (F) List assignment to %ENV is not supported on some systems, notably VMS.

Can't modify %s in %s
    (F) You aren't allowed to assign to the item indicated, or otherwise try to change it, such as with an auto-increment.

Can't modify nonexistent substring
    (P) The internal routine that does assignment to a substr() was handed a NULL.

Can't msgrcv to read-only var
    (F) The target of a msgrcv must be modifiable to be used as a receive buffer.

Can't open %s: %s
    (S) The implicit opening of a file through use of the <> filehandle, either implicitly under the -n or -p command-line switches, or explicitly, failed for the indicated reason. Usually this is because you don't have read permission for a file which you named on the command line.

Can't open bidirectional pipe
    (W) You tried to say open(CMD, "|cmd|"), which is not supported. You can try any of several modules in the Perl library to do this, such as IPC::Open2. Alternately, direct the pipe's output to a file using ">", and then read it in under a different file handle.

Can't open error file %s as stderr
    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '2>' or '2>>' on the command line for writing.

Can't open input file %s as stdin
    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '<' on the command line for reading.

Can't open output file %s as stdout
    (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '>' or '>>' on the command line for writing.

Can't open output pipe (name: %s)
    (P) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the pipe into which to send data destined for stdout.

Can't open perl script
    (F) The script you specified can't be opened for the indicated reason.

Can't redefine active sort subroutine %s
    (F) Perl optimizes the internal handling of sort subroutines and keeps pointers into them. You tried to redefine one such sort subroutine when it was currently active, which is not allowed. If you really want to do this, you should write sort { &func } @x instead of sort func @x.

Can't rename %s to %s: %s, skipping file
    (S) The rename done by the -i switch failed for some reason, probably because you don't have write permission to the directory.

Can't reopen input pipe (name: %s) in binary mode
    (P) An error peculiar to VMS. Perl thought stdin was a pipe, and tried to reopen it to accept binary data. Alas, it failed.

Can't reswap uid and euid
    (P) The setreuid() call failed for some reason in the setuid emulator of suidperl.

Can't return outside a subroutine
    (F) The return statement was executed in mainline code, that is, where there was no subroutine call to return out of. See the perlsub manpage.

Can't stat script
    (P) For some reason you can't fstat() the script even though you have it open already. Bizarre.

Can't swap uid and euid
    (P) The setreuid() call failed for some reason in the setuid emulator of suidperl.

Can't take log of %g
    (F) For ordinary real numbers, you can't take the logarithm of a negative number or zero. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that for the negative numbers.

Can't take sqrt of %g
    (F) For ordinary real numbers, you can't take the square root of a negative number. There's a Math::Complex package that comes standard with Perl, though, if you really want to do that.

Can't undef active subroutine
    (F) You can't undefine a routine that's currently running. You can, however, redefine it while it's running, and you can even undef the redefined subroutine while the old routine is running. Go figure.

Can't unshift
    (F) You tried to unshift an "unreal" array that can't be unshifted, such as the main Perl stack.

Can't upgrade that kind of scalar
    (P) The internal sv_upgrade routine adds "members" to an SV, making it into a more specialized kind of SV. The top several SV types are so specialized, however, that they cannot be interconverted. This message indicates that such a conversion was attempted.

Can't upgrade to undef
    (P) The undefined SV is the bottom of the totem pole, in the scheme of upgradability. Upgrading to undef indicates an error in the code calling sv_upgrade.

Can't use %%! because Errno.pm is not available
    (F) The first time the %! hash is used, perl automatically loads the Errno.pm module. The Errno module is expected to tie the %! hash to provide symbolic names for $! errno values.

Can't use
    (F) The global variables $a and $b are reserved for sort comparisons. You mentioned $a or $b in the same line as the <=> or cmp operator, and the variable had earlier been declared as a lexical variable. Either qualify the sort variable with the package name, or rename the lexical variable.

Can't use %s for loop variable
    (F) Only a simple scalar variable may be used as a loop variable on a foreach.

Can't use %s ref as %s ref
    (F) You've mixed up your reference types. You have to dereference a reference of the type needed. You can use the ref() function to test the type of the reference, if need be.

Can't use \1 to mean $1 in expression
    (W) In an ordinary expression, backslash is a unary operator that creates a reference to its argument. The use of backslash to indicate a backreference to a matched substring is valid only as part of a regular expression pattern. Trying to do this in ordinary Perl code produces a value that prints out looking like SCALAR(0xdecaf). Use the $1 form instead.

Can't use bareword '%s' as %s ref while \"strict refs\
    (F) Only hard references are allowed by "strict refs". Symbolic references are disallowed. See the perlref manpage.

Can't use string '%s' as %s ref while
    (F) Only hard references are allowed by "strict refs". Symbolic references are disallowed. See the perlref manpage.

Can't use an undefined value as %s reference
    (F) A value used as either a hard reference or a symbolic reference must be a defined value. This helps to delurk some insidious errors.

Can't use global %s in
    (F) You tried to declare a magical variable as a lexical variable. This is not allowed, because the magic can be tied to only one location (namely the global variable) and it would be incredibly confusing to have variables in your program that looked like magical variables but weren't.

Can't use subscript on %s
    (F) The compiler tried to interpret a bracketed expression as a subscript. But to the left of the brackets was an expression that didn't look like an array reference, or anything else subscriptable.

Can't x= to read-only value
    (F) You tried to repeat a constant value (often the undefined value) with an assignment operator, which implies modifying the value itself. Perhaps you need to copy the value to a temporary, and repeat that.

Cannot find an opnumber for
    (F) A string of a form CORE::word was given to prototype(), but there is no builtin with the name word.

Cannot resolve method `%s' overloading `%s' in package `%s'
    (F|P) Error resolving overloading specified by a method name (as opposed to a subroutine reference): no such method callable via the package. If method name is ???, this is an internal error.

Character class syntax [. .] is reserved for future extensions
    (W) Within regular expression character classes ([]) the syntax beginning with "[." and ending with ".]" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: "\[." and ".\]".

Character class syntax [: :] is reserved for future extensions
    (W) Within regular expression character classes ([]) the syntax beginning with "[:" and ending with ":]" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: "\[:" and ":\]".

Character class syntax [= =] is reserved for future extensions
    (W) Within regular expression character classes ([]) the syntax beginning with "[=" and ending with "=]" is reserved for future extensions. If you need to represent those character sequences inside a regular expression character class, just quote the square brackets with the backslash: "\[=" and "=\]".

chmod: mode argument is missing initial 0
    (W) A novice will sometimes say

        chmod 777, $filename
    not realizing that 777 will be interpreted as a decimal number, equivalent to 01411. Octal constants are introduced with a leading 0 in Perl, as in C.

Close on unopened file <%s>
    (W) You tried to close a filehandle that was never opened.

Compilation failed in require
    (F) Perl could not compile a file specified in a require statement. Perl uses this generic message when none of the errors that it encountered were severe enough to halt compilation immediately.

Complex regular subexpression recursion limit (%d) exceeded
    (W) The regular expression engine uses recursion in complex situations where back-tracking is required. Recursion depth is limited to 32766, or perhaps less in architectures where the stack cannot grow arbitrarily. ("Simple" and "medium" situations are handled without recursion and are not subject to a limit.) Try shortening the string under examination; looping in Perl code (e.g. with while) rather than in the regular expression engine; or rewriting the regular expression so that it is simpler or backtracks less. (See the perlbook manpage for information on Mastering Regular Expressions.)

connect() on closed fd
    (W) You tried to do a connect on a closed socket. Did you forget to check the return value of your socket() call? See the connect entry in the perlfunc manpage.

Constant subroutine %s redefined
    (S) You redefined a subroutine which had previously been eligible for inlining. See the section on Constant Functions in the perlsub manpage for commentary and workarounds.

Constant subroutine %s undefined
    (S) You undefined a subroutine which had previously been eligible for inlining. See the section on Constant Functions in the perlsub manpage for commentary and workarounds.

Copy method did not return a reference
    (F) The method which overloads "=" is buggy. See the section on Copy Constructor in the overload manpage.

Corrupt malloc ptr 0x%lx at 0x%lx
    (P) The malloc package that comes with Perl had an internal failure.

corrupted regexp pointers
    (P) The regular expression engine got confused by what the regular expression compiler gave it.

corrupted regexp program
    (P) The regular expression engine got passed a regexp program without a valid magic number.

Deep recursion on subroutine
    (W) This subroutine has called itself (directly or indirectly) 100 times more than it has returned. This probably indicates an infinite recursion, unless you're writing strange benchmark programs, in which case it indicates something else.

Delimiter for here document is too long
    (F) In a here document construct like <<FOO, the label FOO is too long for Perl to handle. You have to be seriously twisted to write code that triggers this error.

Did you mean &%s instead?
    (W) You probably referred to an imported subroutine &FOO as $FOO or some such.

Did you mean $ or @ instead of %?
    (W) You probably said %hash{$key} when you meant $hash{$key} or @hash{@keys}. On the other hand, maybe you just meant %hash and got carried away.

Died
    (F) You passed die() an empty string (the equivalent of die "") or you called it with no args and both $@ and $_ were empty.

Do you need to predeclare %s?
    (S) This is an educated guess made in conjunction with the message "%s found where operator expected". It often means a subroutine or module name is being referenced that hasn't been declared yet. This may be because of ordering problems in your file, or because of a missing "sub", "package", "require", or "use" statement. If you're referencing something that isn't defined yet, you don't actually have to define the subroutine or package before the current location. You can use an empty "sub foo;" or "package FOO;" to enter a "forward" declaration.

Don't know how to handle magic of type '%s'
    (P) The internal handling of magical variables has been cursed.

do_study: out of memory
    (P) This should have been caught by safemalloc() instead.

Duplicate free() ignored
    (S) An internal routine called free() on something that had already been freed.

elseif should be elsif
    (S) There is no keyword "elseif" in Perl because Larry thinks it's ugly. Your code will be interpreted as an attempt to call a method named "elseif" for the class returned by the following block. This is unlikely to be what you want.

END failed--cleanup aborted
    (F) An untrapped exception was raised while executing an END subroutine. The interpreter is immediately exited.

Error converting file specification %s
    (F) An error peculiar to VMS. Because Perl may have to deal with file specifications in either VMS or Unix syntax, it converts them to a single form when it must operate on them directly. Either you've passed an invalid file specification to Perl, or you've found a case the conversion routines don't handle. Drat.

%s: Eval-group in insecure regular expression
    (F) Perl detected tainted data when trying to compile a regular expression that contains the (?{ ... }) zero-width assertion, which is unsafe. See the section on (?{ code }) in the perlre manpage, and the perlsec manpage.

%s: Eval-group not allowed, use re 'eval'
    (F) A regular expression contained the (?{ ... }) zero-width assertion, but that construct is only allowed when the use re 'eval' pragma is in effect. See the section on (?{ code }) in the perlre manpage.

%s: Eval-group not allowed at run time
    (F) Perl tried to compile a regular expression containing the (?{ ... }) zero-width assertion at run time, as it would when the pattern contains interpolated values. Since that is a security risk, it is not allowed. If you insist, you may still do this by explicitly building the pattern from an interpolated string at run time and using that in an eval(). See the section on (?{ code }) in the perlre manpage.

Excessively long <> operator
    (F) The contents of a <> operator may not exceed the maximum size of a Perl identifier. If you're just trying to glob a long list of filenames, try using the glob() operator, or put the filenames into a variable and glob that.

Execution of %s aborted due to compilation errors
    (F) The final summary message when a Perl compilation fails.

Exiting eval via %s
    (W) You are exiting an eval by unconventional means, such as a goto, or a loop control statement.

Exiting pseudo-block via %s
    (W) You are exiting a rather special block construct (like a sort block or subroutine) by unconventional means, such as a goto, or a loop control statement. See the sort entry in the perlfunc manpage.

Exiting subroutine via %s
    (W) You are exiting a subroutine by unconventional means, such as a goto, or a loop control statement.

Exiting substitution via %s
    (W) You are exiting a substitution by unconventional means, such as a return, a goto, or a loop control statement.

Explicit blessing to '' (assuming package main)
    (W) You are blessing a reference to a zero length string. This has the effect of blessing the reference into the package main. This is usually not what you want. Consider providing a default target package, e.g. bless($ref, $p or 'MyPackage');

Fatal VMS error at %s, line %d
    (P) An error peculiar to VMS. Something untoward happened in a VMS system service or RTL routine; Perl's exit status should provide more details. The filename in "at %s" and the line number in "line %d" tell you which section of the Perl source code is distressed.

fcntl is not implemented
    (F) Your machine apparently doesn't implement fcntl(). What is this, a PDP-11 or something?

Filehandle %s never opened
    (W) An I/O operation was attempted on a filehandle that was never initialized. You need to do an open() or a socket() call, or call a constructor from the FileHandle package.

Filehandle %s opened for only input
    (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you intended only to write the file, use ">" or ">>". See the open entry in the perlfunc manpage.

Filehandle opened for only input
    (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you intended only to write the file, use ">" or ">>". See the open entry in the perlfunc manpage.

Final $ should be \$ or $name
    (F) You must now decide whether the final $ in a string was meant to be a literal dollar sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name.

Final @ should be \@ or @name
    (F) You must now decide whether the final @ in a string was meant to be a literal "at" sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name.

Format %s redefined
    (W) You redefined a format. To suppress this warning, say

        {
            local $^W = 0;
            eval "format NAME =...";
        }

Format not terminated
    (F) A format must be terminated by a line with a solitary dot. Perl got to the end of your file without finding such a line.

Found = in conditional, should be ==
    (W) You said

        if ($foo = 123)
    when you meant

        if ($foo == 123)
    (or something like that).

gdbm store returned %d, errno %d, key
    (S) A warning from the GDBM_File extension that a store failed.

gethostent not implemented
    (F) Your C library apparently doesn't implement gethostent(), probably because if it did, it'd feel morally obligated to return every hostname on the Internet.

get{sock,peer}name() on closed fd
    (W) You tried to get a socket or peer socket name on a closed socket. Did you forget to check the return value of your socket() call?

getpwnam returned invalid UIC %#o for user
    (S) A warning peculiar to VMS. The call to sys$getuai underlying the getpwnam operator returned an invalid UIC.

Glob not terminated
    (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than".

Global symbol
    (F) You've said "use strict vars", which indicates that all variables must either be lexically scoped (using "my"), or explicitly qualified to say which package the global variable is in (using "::").

goto must have label
    (F) Unlike with "next" or "last", you're not allowed to goto an unspecified destination. See the goto entry in the perlfunc manpage.

Had to create %s unexpectedly
    (S) A routine asked for a symbol from a symbol table that ought to have existed already, but for some reason it didn't, and had to be created on an emergency basis to prevent a core dump.

Hash %%s missing the % in argument %d of %s()
    (D) Really old Perl let you omit the % on hash names in some spots. This is now heavily deprecated.

Identifier too long
    (F) Perl limits identifiers (names for variables, functions, etc.) to about 250 characters for simple names, and somewhat more for compound names (like $A::B). You've exceeded Perl's limits. Future versions of Perl are likely to eliminate these arbitrary limitations.

Ill-formed logical name |%s| in prime_env_iter
    (W) A warning peculiar to VMS. A logical name was encountered when preparing to iterate over %ENV which violates the syntactic rules governing logical names. Because it cannot be translated normally, it is skipped, and will not appear in %ENV. This may be a benign occurrence, as some software packages might directly modify logical name tables and introduce nonstandard names, or it may indicate that a logical name table has been corrupted.

Illegal character %s (carriage return)
    (F) A carriage return character was found in the input. This is an error, and not a warning, because carriage return characters can break multi-line strings, including here documents (e.g., print <<EOF;).

    Under Unix, this error is usually caused by executing Perl code -- either the main program, a module, or an eval'd string -- that was transferred over a network connection from a non-Unix system without properly converting the text file format.

    Under systems that use something other than '\n' to delimit lines of text, this error can also be caused by reading Perl code from a file handle that is in binary mode (as set by the binmode operator).

    In either case, the Perl code in question will probably need to be converted with something like s/\x0D\x0A?/\n/g before it can be executed.

Illegal division by zero
    (F) You tried to divide a number by 0. Either something was wrong in your logic, or you need to put a conditional in to guard against meaningless input.

Illegal modulus zero
    (F) You tried to divide a number by 0 to get the remainder. Most numbers don't take to this kindly.

Illegal octal digit
    (F) You used an 8 or 9 in a octal number.

Illegal octal digit ignored
    (W) You may have tried to use an 8 or 9 in a octal number. Interpretation of the octal number stopped before the 8 or 9.

Illegal hex digit ignored
    (W) You may have tried to use a character other than 0 - 9 or A - F in a hexadecimal number. Interpretation of the hexadecimal number stopped before the illegal character.

Illegal switch in PERL5OPT: %s
    (X) The PERL5OPT environment variable may only be used to set the following switches: -[DIMUdmw].

In string, @%s now must be written as \@%s
    (F) It used to be that Perl would try to guess whether you wanted an array interpolated or a literal @. It did this when the string was first used at runtime. Now strings are parsed at compile time, and ambiguous instances of @ must be disambiguated, either by prepending a backslash to indicate a literal, or by declaring (or using) the array within the program before the string (lexically). (Someday it will simply assume that an unbackslashed @ interpolates an array.)

Insecure dependency in %s
    (F) You tried to do something that the tainting mechanism didn't like. The tainting mechanism is turned on when you're running setuid or setgid, or when you specify -T to turn it on explicitly. The tainting mechanism labels all data that's derived directly or indirectly from the user, who is considered to be unworthy of your trust. If any such data is used in a "dangerous" operation, you get this error. See the perlsec manpage for more information.

Insecure directory in %s
    (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if $ENV{PATH} contains a directory that is writable by the world. See the perlsec manpage.

Insecure $ENV{%s} while running %s
    (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if any of $ENV{PATH}, $ENV{IFS}, $ENV{CDPATH}, $ENV{ENV} or $ENV{BASH_ENV} are derived from data supplied (or potentially supplied) by the user. The script must set the path to a known value, using trustworthy data. See the perlsec manpage.

Integer overflow in hex number
    (S) The literal hex number you have specified is too big for your architecture. On a 32-bit architecture the largest hex literal is 0xFFFFFFFF.

Integer overflow in octal number
    (S) The literal octal number you have specified is too big for your architecture. On a 32-bit architecture the largest octal literal is 037777777777.

Internal inconsistency in tracking vforks
    (S) A warning peculiar to VMS. Perl keeps track of the number of times you've called fork and exec, to determine whether the current call to exec should affect the current script or a subprocess (see the exec entry in the perlvms manpage). Somehow, this count has become scrambled, so Perl is making a guess and treating this exec as a request to terminate the Perl script and execute the specified command.

internal disaster in regexp
    (P) Something went badly wrong in the regular expression parser.

internal error: glob failed
    (P) Something went wrong with the external program(s) used for glob and <*.c>. This may mean that your csh (C shell) is broken. If so, you should change all of the csh-related variables in config.sh: If you have tcsh, make the variables refer to it as if it were csh (e.g. full_csh='/usr/bin/tcsh'); otherwise, make them all empty (except that d_csh should be 'undef') so that Perl will think csh is missing. In either case, after editing config.sh, run ./Configure -S and rebuild Perl.

internal urp in regexp at /%s/
    (P) Something went badly awry in the regular expression parser.

invalid [] range in regexp
    (F) The range specified in a character class had a minimum character greater than the maximum character. See the perlre manpage.

Invalid conversion in %s:
    (W) Perl does not understand the given format conversion. See the sprintf entry in the perlfunc manpage.

Invalid type in pack: '%s'
    (F) The given character is not a valid pack type. See the pack entry in the perlfunc manpage. (W) The given character is not a valid pack type but used to be silently ignored.

Invalid type in unpack: '%s'
    (F) The given character is not a valid unpack type. See the unpack entry in the perlfunc manpage. (W) The given character is not a valid unpack type but used to be silently ignored.

ioctl is not implemented
    (F) Your machine apparently doesn't implement ioctl(), which is pretty strange for a machine that supports C.

junk on end of regexp
    (P) The regular expression parser is confused.

Label not found for
    (F) You named a loop to break out of, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage.

Label not found for
    (F) You named a loop to continue, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage.

Label not found for
    (F) You named a loop to restart, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage.

listen() on closed fd
    (W) You tried to do a listen on a closed socket. Did you forget to check the return value of your socket() call? See the listen entry in the perlfunc manpage.

Method for operation %s not found in package %s during blessing
    (F) An attempt was made to specify an entry in an overloading table that doesn't resolve to a valid subroutine. See the overload manpage.

Might be a runaway multi-line %s string starting on line %d
    (S) An advisory indicating that the previous error may have been caused by a missing delimiter on a string or pattern, because it eventually ended earlier on the current line.

Misplaced _ in number
    (W) An underline in a decimal constant wasn't on a 3-digit boundary.

Missing $ on loop variable
    (F) Apparently you've been programming in csh too much. Variables are always mentioned with the $ in Perl, unlike in the shells, where it can vary from one line to the next.

Missing comma after first argument to %s function
    (F) While certain functions allow you to specify a filehandle or an "indirect object" before the argument list, this ain't one of them.

Missing operator before %s?
    (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Often the missing operator is a comma.

Missing right bracket
    (F) The lexer counted more opening curly brackets (braces) than closing ones. As a general rule, you'll find it's missing near the place you were last editing.

Modification of a read-only value attempted
    (F) You tried, directly or indirectly, to change the value of a constant. You didn't, of course, try "2 = 1", because the compiler catches that. But an easy way to do the same thing is:

        sub mod { $_[0] = 1 }
        mod(2);
    Another way is to assign to a substr() that's off the end of the string.

Modification of non-creatable array value attempted, subscript %d
    (F) You tried to make an array value spring into existence, and the subscript was probably negative, even counting from end of the array backwards.

Modification of non-creatable hash value attempted, subscript
    (P) You tried to make a hash value spring into existence, and it couldn't be created for some peculiar reason.

Module name must be constant
    (F) Only a bare module name is allowed as the first argument to a "use".

msg%s not implemented
    (F) You don't have System V message IPC on your system.

Multidimensional syntax %s not supported
    (W) Multidimensional arrays aren't written like $foo[1,2,3]. They're written like $foo[1][2][3], as in C.

Name
    (W) Typographical errors often show up as unique variable names. If you had a good reason for having a unique name, then just mention it again somehow to suppress the message. The use vars pragma is provided for just this purpose.

Negative length
    (F) You tried to do a read/write/send/recv operation with a buffer length that is less than 0. This is difficult to imagine.

nested *?+ in regexp
    (F) You can't quantify a quantifier without intervening parentheses. So things like ** or +* or ?* are illegal.

    Note, however, that the minimal matching quantifiers, *?, +?, and ?? appear to be nested quantifiers, but aren't. See the perlre manpage.

No #! line
    (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct.

No %s allowed while running setuid
    (F) Certain operations are deemed to be too insecure for a setuid or setgid script to even be allowed to attempt. Generally speaking there will be another way to do what you want that is, if not secure, at least securable. See the perlsec manpage.

No -e allowed in setuid scripts
    (F) A setuid script can't be specified by the user.

No comma allowed after %s
    (F) A list operator that has a filehandle or "indirect object" is not allowed to have a comma between that and the following arguments. Otherwise it'd be just another one of the arguments.

    One possible cause for this is that you expected to have imported a constant to your name space with use or import while no such importing took place, it may for example be that your operating system does not support that particular constant. Hopefully you did use an explicit import list for the constants you expect to see, please see the use entry in the perlfunc manpage and the import entry in the perlfunc manpage. While an explicit import list would probably have caught this error earlier it naturally does not remedy the fact that your operating system still does not support that constant. Maybe you have a typo in the constants of the symbol import list of use or import or in the constant name at the line where this error was triggered?

No command into which to pipe on command line
    (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '|' at the end of the command line, so it doesn't know where you want to pipe the output from this command.

No DB::DB routine defined
    (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a routine to be called at the beginning of each statement. Which is odd, because the file should have been required automatically, and should have blown up the require if it didn't parse right.

No dbm on this machine
    (P) This is counted as an internal error, because every machine should supply dbm nowadays, because Perl comes with SDBM. See the SDBM_File manpage.

No DBsub routine
    (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a DB::sub routine to be called at the beginning of each ordinary subroutine call.

No error file after 2> or 2>> on command line
    (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '2>' or a '2>>' on the command line, but can't find the name of the file to which to write data destined for stderr.

No input file after < on command line
    (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '<' on the command line, but can't find the name of the file from which to read data for stdin.

No output file after > on command line
    (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a lone '>' at the end of the command line, so it doesn't know where you wanted to redirect stdout.

No output file after > or >> on command line
    (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '>' or a '>>' on the command line, but can't find the name of the file to which to write data destined for stdout.

No Perl script found in input
    (F) You called perl -x, but no line was found in the file beginning with #! and containing the word "perl".

No setregid available
    (F) Configure didn't find anything resembling the setregid() call for your system.

No setreuid available
    (F) Configure didn't find anything resembling the setreuid() call for your system.

No space allowed after -I
    (F) The argument to -I must follow the -I immediately with no intervening space.

No such array field
    (F) You tried to access an array as a hash, but the field name used is not defined. The hash at index 0 should map all valid field names to array indices for that to work.

No such field
    (F) You tried to access a field of a typed variable where the type does not know about the field name. The field names are looked up in the %FIELDS hash in the type package at compile time. The %FIELDS hash is usually set up with the 'fields' pragma.

No such pipe open
    (P) An error peculiar to VMS. The internal routine my_pclose() tried to close a pipe which hadn't been opened. This should have been caught earlier as an attempt to close an unopened filehandle.

No such signal: SIG%s
    (W) You specified a signal name as a subscript to %SIG that was not recognized. Say kill -l in your shell to see the valid signal names on your system.

Not a CODE reference
    (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage.

Not a format reference
    (F) I'm not sure how you managed to generate a reference to an anonymous format, but this indicates you did, and that it didn't exist.

Not a GLOB reference
    (F) Perl was trying to evaluate a reference to a "typeglob" (that is, a symbol table entry that looks like *foo), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage.

Not a HASH reference
    (F) Perl was trying to evaluate a reference to a hash value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage.

Not a perl script
    (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct. The line must mention perl.

Not a SCALAR reference
    (F) Perl was trying to evaluate a reference to a scalar value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage.

Not a subroutine reference
    (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage.

Not a subroutine reference in overload table
    (F) An attempt was made to specify an entry in an overloading table that doesn't somehow point to a valid subroutine. See the overload manpage.

Not an ARRAY reference
    (F) Perl was trying to evaluate a reference to an array value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage.

Not enough arguments for %s
    (F) The function requires more arguments than you specified.

Not enough format arguments
    (W) A format specified more picture fields than the next line supplied. See the perlform manpage.

Null filename used
    (F) You can't require the null filename, especially because on many machines that means the current directory! See the require entry in the perlfunc manpage.

Null picture in formline
    (F) The first argument to formline must be a valid format picture specification. It was found to be empty, which probably means you supplied it an uninitialized value. See the perlform manpage.

NULL OP IN RUN
    (P) Some internal routine called run() with a null opcode pointer.

Null realloc
    (P) An attempt was made to realloc NULL.

NULL regexp argument
    (P) The internal pattern matching routines blew it big time.

NULL regexp parameter
    (P) The internal pattern matching routines are out of their gourd.

Number too long
    (F) Perl limits the representation of decimal numbers in programs to about about 250 characters. You've exceeded that length. Future versions of Perl are likely to eliminate this arbitrary limitation. In the meantime, try using scientific notation (e.g. "1e6" instead of "1_000_000").

Odd number of elements in hash assignment
    (S) You specified an odd number of elements to initialize a hash, which is odd, because hashes come in key/value pairs.

Offset outside string
    (F) You tried to do a read/write/send/recv operation with an offset pointing outside the buffer. This is difficult to imagine. The sole exception to this is that sysread()ing past the buffer will extend the buffer and zero pad the new area.

oops: oopsAV
    (S) An internal warning that the grammar is screwed up.

oops: oopsHV
    (S) An internal warning that the grammar is screwed up.

Operation `%s': no method found, %s
    (F) An attempt was made to perform an overloaded operation for which no handler was defined. While some handlers can be autogenerated in terms of other handlers, there is no default handler for any operation, unless fallback overloading key is specified to be true. See the overload manpage.

Operator or semicolon missing before %s
    (S) You used a variable or subroutine call where the parser was expecting an operator. The parser has assumed you really meant to use an operator, but this is highly likely to be incorrect. For example, if you say "*foo *foo" it will be interpreted as if you said "*foo * 'foo'".

Out of memory for yacc stack
    (F) The yacc parser wanted to grow its stack so it could continue parsing, but realloc() wouldn't give it more memory, virtual or otherwise.

Out of memory during request for %s
    (X|F) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request.

    The request was judged to be small, so the possibility to trap it depends on the way perl was compiled. By default it is not trappable. However, if compiled for this, Perl may use the contents of $^M as an emergency pool after die()ing with this message. In this case the error is trappable once.

Out of memory during
    (F) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request. However, the request was judged large enough (compile-time default is 64K), so a possibility to shut down by trapping this error is granted.

Out of memory during ridiculously large request
    (F) You can't allocate more than 2^31+"small amount" bytes. This error is most likely to be caused by a typo in the Perl program. e.g., $arr[time] instead of $arr[$time].

page overflow
    (W) A single call to write() produced more lines than can fit on a page. See the perlform manpage.

panic: ck_grep
    (P) Failed an internal consistency check trying to compile a grep.

panic: ck_split
    (P) Failed an internal consistency check trying to compile a split.

panic: corrupt saved stack index
    (P) The savestack was requested to restore more localized values than there are in the savestack.

panic: die %s
    (P) We popped the context stack to an eval context, and then discovered it wasn't an eval context.

panic: do_match
    (P) The internal pp_match() routine was called with invalid operational data.

panic: do_split
    (P) Something terrible went wrong in setting up for the split.

panic: do_subst
    (P) The internal pp_subst() routine was called with invalid operational data.

panic: do_trans
    (P) The internal do_trans() routine was called with invalid operational data.

panic: frexp
    (P) The library function frexp() failed, making printf("%f") impossible.

panic: goto
    (P) We popped the context stack to a context with the specified label, and then discovered it wasn't a context we know how to do a goto in.

panic: INTERPCASEMOD
    (P) The lexer got into a bad state at a case modifier.

panic: INTERPCONCAT
    (P) The lexer got into a bad state parsing a string with brackets.

panic: last
    (P) We popped the context stack to a block context, and then discovered it wasn't a block context.

panic: leave_scope clearsv
    (P) A writable lexical variable became read-only somehow within the scope.

panic: leave_scope inconsistency
    (P) The savestack probably got out of sync. At least, there was an invalid enum on the top of it.

panic: malloc
    (P) Something requested a negative number of bytes of malloc.

panic: mapstart
    (P) The compiler is screwed up with respect to the map() function.

panic: null array
    (P) One of the internal array routines was passed a null AV pointer.

panic: pad_alloc
    (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from.

panic: pad_free curpad
    (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from.

panic: pad_free po
    (P) An invalid scratch pad offset was detected internally.

panic: pad_reset curpad
    (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from.

panic: pad_sv po
    (P) An invalid scratch pad offset was detected internally.

panic: pad_swipe curpad
    (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from.

panic: pad_swipe po
    (P) An invalid scratch pad offset was detected internally.

panic: pp_iter
    (P) The foreach iterator got called in a non-loop context frame.

panic: realloc
    (P) Something requested a negative number of bytes of realloc.

panic: restartop
    (P) Some internal routine requested a goto (or something like it), and didn't supply the destination.

panic: return
    (P) We popped the context stack to a subroutine or eval context, and then discovered it wasn't a subroutine or eval context.

panic: scan_num
    (P) scan_num() got called on something that wasn't a number.

panic: sv_insert
    (P) The sv_insert() routine was told to remove more string than there was string.

panic: top_env
    (P) The compiler attempted to do a goto, or something weird like that.

panic: yylex
    (P) The lexer got into a bad state while processing a case modifier.

Parentheses missing around
    (W) You said something like

        my $foo, $bar = @_;
    when you meant

        my ($foo, $bar) = @_;
    Remember that "my" and "local" bind closer than comma.

Perl %3.3f required--this is only version %s, stopped
    (F) The module in question uses features of a version of Perl more recent than the currently running version. How long has it been since you upgraded, anyway? See the require entry in the perlfunc manpage.

Permission denied
    (F) The setuid emulator in suidperl decided you were up to no good.

pid %d not a child
    (W) A warning peculiar to VMS. Waitpid() was asked to wait for a process which isn't a subprocess of the current process. While this is fine from VMS' perspective, it's probably not what you intended.

POSIX getpgrp can't take an argument
    (F) Your C compiler uses POSIX getpgrp(), which takes no argument, unlike the BSD version, which takes a pid.

Possible attempt to put comments in qw() list
    (W) qw() lists contain items separated by whitespace; as with literal strings, comment characters are not ignored, but are instead treated as literal data. (You may have used different delimiters than the parentheses shown here; braces are also frequently used.)

    You probably wrote something like this:

        @list = qw(
            a # a comment
            b # another comment
        );
    when you should have written this:

        @list = qw(
            a
            b
        );
    If you really want comments, build your list the old-fashioned way, with quotes and commas:

        @list = (
            'a',    # a comment
            'b',    # another comment
        );

Possible attempt to separate words with commas
    (W) qw() lists contain items separated by whitespace; therefore commas aren't needed to separate the items. (You may have used different delimiters than the parentheses shown here; braces are also frequently used.)

    You probably wrote something like this:

        qw! a, b, c !;
    which puts literal commas into some of the list items. Write it without commas if you don't want them to appear in your data:

        qw! a b c !;

Possible memory corruption: %s overflowed 3rd argument
    (F) An ioctl() or fcntl() returned more than Perl was bargaining for. Perl guesses a reasonable buffer size, but puts a sentinel byte at the end of the buffer just in case. This sentinel byte got clobbered, and Perl assumes that memory is now corrupted. See the ioctl entry in the perlfunc manpage.

Precedence problem: open %s should be open(%s)
    (S) The old irregular construct

        open FOO || die;
    is now misinterpreted as

        open(FOO || die);
    because of the strict regularization of Perl 5's grammar into unary and list operators. (The old open was a little of both.) You must put parentheses around the filehandle, or use the new "or" operator instead of "||".

print on closed filehandle %s
    (W) The filehandle you're printing on got itself closed sometime before now. Check your logic flow.

printf on closed filehandle %s
    (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow.

Probable precedence problem on %s
    (W) The compiler found a bareword where it expected a conditional, which often indicates that an || or && was parsed as part of the last argument of the previous construct, for example:

        open FOO || die;

Prototype mismatch: %s vs %s
    (S) The subroutine being declared or defined had previously been declared or defined with a different function prototype.

Range iterator outside integer range
    (F) One (or both) of the numeric arguments to the range operator ".." are outside the range which can be represented by integers internally. One possible workaround is to force Perl to use magical string increment by prepending "0" to your numbers.

Read on closed filehandle <%s>
    (W) The filehandle you're reading from got itself closed sometime before now. Check your logic flow.

Reallocation too large: %lx
    (F) You can't allocate more than 64K on an MS-DOS machine.

Recompile perl with -DDEBUGGING to use -D switch
    (F) You can't use the -D option unless the code to produce the desired output is compiled into Perl, which entails some overhead, which is why it's currently left out of your copy.

Recursive inheritance detected in package '%s'
    (F) More than 100 levels of inheritance were used. Probably indicates an unintended loop in your inheritance hierarchy.

Recursive inheritance detected while looking for method '%s' in package '%s'
    (F) More than 100 levels of inheritance were encountered while invoking a method. Probably indicates an unintended loop in your inheritance hierarchy.

Reference found where even-sized list expected
    (W) You gave a single reference where Perl was expecting a list with an even number of elements (for assignment to a hash). This usually means that you used the anon hash constructor when you meant to use parens. In any case, a hash requires key/value pairs.

        %hash = { one => 1, two => 2, };    # WRONG
        %hash = [ qw/ an anon array / ];    # WRONG
        %hash = ( one => 1, two => 2, );    # right
        %hash = qw( one 1 two 2 );                  # also fine

Reference miscount in sv_replace()
    (W) The internal sv_replace() function was handed a new SV with a reference count of other than 1.

regexp *+ operand could be empty
    (F) The part of the regexp subject to either the * or + quantifier could match an empty string.

regexp memory corruption
    (P) The regular expression engine got confused by what the regular expression compiler gave it.

regexp out of space
    (P) A "can't happen" error, because safemalloc() should have caught it earlier.

regexp too big
    (F) The current implementation of regular expressions uses shorts as address offsets within a string. Unfortunately this means that if the regular expression compiles to longer than 32767, it'll blow up. Usually when you want a regular expression this big, there is a better way to do it with multiple statements. See the perlre manpage.

Reversed %s= operator
    (W) You wrote your assignment operator backwards. The = must always comes last, to avoid ambiguity with subsequent unary operators.

Runaway format
    (F) Your format contained the ~~ repeat-until-blank sequence, but it produced 200 lines at once, and the 200th line looked exactly like the 199th line. Apparently you didn't arrange for the arguments to exhaust themselves, either by using ^ instead of @ (for scalar variables), or by shifting or popping (for array variables). See the perlform manpage.

Scalar value @%s[%s] better written as $%s[%s]
    (W) You've used an array slice (indicated by @) to select a single element of an array. Generally it's better to ask for a scalar value (indicated by $). The difference is that $foo[&bar] always behaves like a scalar, both when assigning to it and when evaluating its argument, while @foo[&bar] behaves like a list when you assign to it, and provides a list context to its subscript, which can do weird things if you're expecting only one subscript.

    On the other hand, if you were actually hoping to treat the array element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage.

Scalar value @%s{%s} better written as $%s{%s}
    (W) You've used a hash slice (indicated by @) to select a single element of a hash. Generally it's better to ask for a scalar value (indicated by $). The difference is that $foo{&bar} always behaves like a scalar, both when assigning to it and when evaluating its argument, while @foo{&bar} behaves like a list when you assign to it, and provides a list context to its subscript, which can do weird things if you're expecting only one subscript.

    On the other hand, if you were actually hoping to treat the hash element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage.

Script is not setuid/setgid in suidperl
    (F) Oddly, the suidperl program was invoked on a script without a setuid or setgid bit set. This doesn't make much sense.

Search pattern not terminated
    (F) The lexer couldn't find the final delimiter of a // or m{} construct. Remember that bracketing delimiters count nesting level. Missing the leading $ from a variable $m may cause this error.

%sseek() on unopened file
    (W) You tried to use the seek() or sysseek() function on a filehandle that was either never opened or has since been closed.

select not implemented
    (F) This machine doesn't implement the select() system call.

sem%s not implemented
    (F) You don't have System V semaphore IPC on your system.

semi-panic: attempt to dup freed string
    (S) The internal newSVsv() routine was called to duplicate a scalar that had previously been marked as free.

Semicolon seems to be missing
    (W) A nearby syntax error was probably caused by a missing semicolon, or possibly some other missing operator, such as a comma.

Send on closed socket
    (W) The filehandle you're sending to got itself closed sometime before now. Check your logic flow.

Sequence (? incomplete
    (F) A regular expression ended with an incomplete extension (?. See the perlre manpage.

Sequence (?#... not terminated
    (F) A regular expression comment must be terminated by a closing parenthesis. Embedded parentheses aren't allowed. See the perlre manpage.

Sequence (?%s...) not implemented
    (F) A proposed regular expression extension has the character reserved but has not yet been written. See the perlre manpage.

Sequence (?%s...) not recognized
    (F) You used a regular expression extension that doesn't make sense. See the perlre manpage.

Server error
    Also known as "500 Server error".

    This is a CGI error, not a Perl error.

    You need to make sure your script is executable, is accessible by the user CGI is running the script under (which is probably not the user account you tested it under), does not rely on any environment variables (like PATH) from the user it isn't running under, and isn't in a location where the CGI server can't find it, basically, more or less. Please see the following for more information:

            http://www.perl.com/perl/faq/idiots-guide.html
            http://www.perl.com/perl/faq/perl-cgi-faq.html
            ftp://rtfm.mit.edu/pub/usenet/news.answers/www/cgi-faq
            http://hoohoo.ncsa.uiuc.edu/cgi/interface.html
            http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html

setegid() not implemented
    (F) You tried to assign to $), and your operating system doesn't support the setegid() system call (or equivalent), or at least Configure didn't think so.

seteuid() not implemented
    (F) You tried to assign to $>, and your operating system doesn't support the seteuid() system call (or equivalent), or at least Configure didn't think so.

setrgid() not implemented
    (F) You tried to assign to $(, and your operating system doesn't support the setrgid() system call (or equivalent), or at least Configure didn't think so.

setruid() not implemented
    (F) You tried to assign to $<, and your operating system doesn't support the setruid() system call (or equivalent), or at least Configure didn't think so.

Setuid/gid script is writable by world
    (F) The setuid emulator won't run a script that is writable by the world, because the world might have written on it already.

shm%s not implemented
    (F) You don't have System V shared memory IPC on your system.

shutdown() on closed fd
    (W) You tried to do a shutdown on a closed socket. Seems a bit superfluous.

SIG%s handler
    (W) The signal handler named in %SIG doesn't, in fact, exist. Perhaps you put it into the wrong package?

sort is now a reserved word
    (F) An ancient error message that almost nobody ever runs into anymore. But before sort was a keyword, people sometimes used it as a filehandle.

Sort subroutine didn't return a numeric value
    (F) A sort comparison routine must return a number. You probably blew it by not using <=> or cmp, or by not using them correctly. See the sort entry in the perlfunc manpage.

Sort subroutine didn't return single value
    (F) A sort comparison subroutine may not return a list value with more or less than one element. See the sort entry in the perlfunc manpage.

Split loop
    (P) The split was looping infinitely. (Obviously, a split shouldn't iterate more times than there are characters of input, which is what happened.) See the split entry in the perlfunc manpage.

Stat on unopened file <%s>
    (W) You tried to use the stat() function (or an equivalent file test) on a filehandle that was either never opened or has since been closed.

Statement unlikely to be reached
    (W) You did an exec() with some statement after it other than a die(). This is almost always an error, because exec() never returns unless there was a failure. You probably wanted to use system() instead, which does return. To suppress this warning, put the exec() in a block by itself.

Stub found while resolving method `%s' overloading `%s' in package `%s'
    (P) Overloading resolution over @ISA tree may be broken by importation stubs. Stubs should never be implicitely created, but explicit calls to can may break this.

Subroutine %s redefined
    (W) You redefined a subroutine. To suppress this warning, say

        {
            local $^W = 0;
            eval "sub name { ... }";
        }

Substitution loop
    (P) The substitution was looping infinitely. (Obviously, a substitution shouldn't iterate more times than there are characters of input, which is what happened.) See the discussion of substitution in the section on Quote and Quote-like Operators in the perlop manpage.

Substitution pattern not terminated
    (F) The lexer couldn't find the interior delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. Missing the leading $ from variable $s may cause this error.

Substitution replacement not terminated
    (F) The lexer couldn't find the final delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. Missing the leading $ from variable $s may cause this error.

substr outside of string
    (S),(W) You tried to reference a substr() that pointed outside of a string. That is, the absolute value of the offset was larger than the length of the string. See the substr entry in the perlfunc manpage. This warning is mandatory if substr is used in an lvalue context (as the left hand side of an assignment or as a subroutine argument for example).

suidperl is no longer needed since %s
    (F) Your Perl was compiled with -DSETUID_SCRIPTS_ARE_SECURE_NOW, but a version of the setuid emulator somehow got run anyway.

syntax error
    (F) Probably means you had a syntax error. Common reasons include:

        A keyword is misspelled.
        A semicolon is missing.
        A comma is missing.
        An opening or closing parenthesis is missing.
        An opening or closing brace is missing.
        A closing quote is missing.
    Often there will be another error message associated with the syntax error giving more information. (Sometimes it helps to turn on -w.) The error message itself often tells you where it was in the line when it decided to give up. Sometimes the actual error is several tokens before this, because Perl is good at understanding random input. Occasionally the line number may be misleading, and once in a blue moon the only way to figure out what's triggering the error is to call perl -c repeatedly, chopping away half the program each time to see if the error went away. Sort of the cybernetic version of 20 questions.

syntax error at line %d: `%s' unexpected
    (A) You've accidentally run your script through the Bourne shell instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

System V %s is not implemented on this machine
    (F) You tried to do something with a function beginning with "sem", "shm", or "msg" but that System V IPC is not implemented in your machine. In some machines the functionality can exist but be unconfigured. Consult your system support.

Syswrite on closed filehandle
    (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow.

Target of goto is too deeply nested
    (F) You tried to use goto to reach a label that was too deeply nested for Perl to reach. Perl is doing you a favor by refusing.

tell() on unopened file
    (W) You tried to use the tell() function on a filehandle that was either never opened or has since been closed.

Test on unopened file <%s>
    (W) You tried to invoke a file test operator on a filehandle that isn't open. Check your logic. See also the section on -X in the perlfunc manpage.

That use of $[ is unsupported
    (F) Assignment to $[ is now strictly circumscribed, and interpreted as a compiler directive. You may say only one of

        $[ = 0;
        $[ = 1;
        ...
        local $[ = 0;
        local $[ = 1;
        ...
    This is to prevent the problem of one module changing the array base out from under another module inadvertently. See the section on $[ in the perlvar manpage.

The %s function is unimplemented
    The function indicated isn't implemented on this architecture, according to the probings of Configure.

The crypt() function is unimplemented due to excessive paranoia
    (F) Configure couldn't find the crypt() function on your machine, probably because your vendor didn't supply it, probably because they think the U.S. Government thinks it's a secret, or at least that they will continue to pretend that it is. And if you quote me on that, I will deny it.

The stat preceding -l _ wasn't an lstat
    (F) It makes no sense to test the current stat buffer for symbolic linkhood if the last stat that wrote to the stat buffer already went past the symlink to get to the real file. Use an actual filename instead.

times not implemented
    (F) Your version of the C library apparently doesn't do times(). I suspect you're not running on Unix.

Too few args to syscall
    (F) There has to be at least one argument to syscall() to specify the system call to call, silly dilly.

Too late for
    (X) The #! line (or local equivalent) in a Perl script contains the -T option, but Perl was not invoked with -T in its command line. This is an error because, by the time Perl discovers a -T in a script, it's too late to properly taint everything from the environment. So Perl gives up.

    If the Perl script is being executed as a command using the #! mechanism (or its local equivalent), this error can usually be fixed by editing the #! line so that the -T option is a part of Perl's first argument: e.g. change perl -n -T to perl -T -n.

    If the Perl script is being executed as perl scriptname, then the -T option must appear on the command line: perl -T scriptname.

Too late for
    (X) The #! line (or local equivalent) in a Perl script contains the -M or -m option. This is an error because -M and -m options are not intended for use inside scripts. Use the use pragma instead.

Too many ('s

Too many )'s
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

Too many args to syscall
    (F) Perl supports a maximum of only 14 args to syscall().

Too many arguments for %s
    (F) The function requires fewer arguments than you specified.

trailing \ in regexp
    (F) The regular expression ends with an unbackslashed backslash. Backslash it. See the perlre manpage.

Transliteration pattern not terminated
    (F) The lexer couldn't find the interior delimiter of a tr/// or tr[][] or y/// or y[][] construct. Missing the leading $ from variables $tr or $y may cause this error.

Transliteration replacement not terminated
    (F) The lexer couldn't find the final delimiter of a tr/// or tr[][] construct.

truncate not implemented
    (F) Your machine doesn't implement a file truncation mechanism that Configure knows about.

Type of arg %d to %s must be %s (not %s)
    (F) This function requires the argument in that position to be of a certain type. Arrays must be @NAME or @{EXPR}. Hashes must be %NAME or %{EXPR}. No implicit dereferencing is allowed--use the {EXPR} forms as an explicit dereference. See the perlref manpage.

umask: argument is missing initial 0
    (W) A umask of 222 is incorrect. It should be 0222, because octal literals always start with 0 in Perl, as in C.

umask not implemented
    (F) Your machine doesn't implement the umask function and you tried to use it to restrict permissions for yourself (EXPR & 0700).

Unable to create sub named
    (F) You attempted to create or access a subroutine with an illegal name.

Unbalanced context: %d more PUSHes than POPs
    (W) The exit code detected an internal inconsistency in how many execution contexts were entered and left.

Unbalanced saves: %d more saves than restores
    (W) The exit code detected an internal inconsistency in how many values were temporarily localized.

Unbalanced scopes: %d more ENTERs than LEAVEs
    (W) The exit code detected an internal inconsistency in how many blocks were entered and left.

Unbalanced tmps: %d more allocs than frees
    (W) The exit code detected an internal inconsistency in how many mortal scalars were allocated and freed.

Undefined format
    (F) The format indicated doesn't seem to exist. Perhaps it's really in another package? See the perlform manpage.

Undefined sort subroutine
    (F) The sort comparison routine specified doesn't seem to exist. Perhaps it's in a different package? See the sort entry in the perlfunc manpage.

Undefined subroutine &%s called
    (F) The subroutine indicated hasn't been defined, or if it was, it has since been undefined.

Undefined subroutine called
    (F) The anonymous subroutine you're trying to call hasn't been defined, or if it was, it has since been undefined.

Undefined subroutine in sort
    (F) The sort comparison routine specified is declared but doesn't seem to have been defined yet. See the sort entry in the perlfunc manpage.

Undefined top format
    (F) The format indicated doesn't seem to exist. Perhaps it's really in another package? See the perlform manpage.

Undefined value assigned to typeglob
    (W) An undefined value was assigned to a typeglob, a la *foo = undef. This does nothing. It's possible that you really mean undef *foo.

unexec of %s into %s failed!
    (F) The unexec() routine failed for some reason. See your local FSF representative, who probably put it there in the first place.

Unknown BYTEORDER
    (F) There are no byte-swapping functions for a machine with this byte order.

unmatched () in regexp
    (F) Unbackslashed parentheses must always be balanced in regular expressions. If you're a vi user, the % key is valuable for finding the matching parenthesis. See the perlre manpage.

Unmatched right bracket
    (F) The lexer counted more closing curly brackets (braces) than opening ones, so you're probably missing an opening bracket. As a general rule, you'll find the missing one (so to speak) near the place you were last editing.

unmatched [] in regexp
    (F) The brackets around a character class must match. If you wish to include a closing bracket in a character class, backslash it or put it first. See the perlre manpage.

Unquoted string
    (W) You used a bareword that might someday be claimed as a reserved word. It's best to put such a word in quotes, or capitalize it somehow, or insert an underbar into it. You might also declare it as a subroutine.

Unrecognized character %s
    (F) The Perl parser has no idea what to do with the specified character in your Perl script (or eval). Perhaps you tried to run a compressed script, a binary program, or a directory as a Perl program.

Unrecognized signal name
    (F) You specified a signal name to the kill() function that was not recognized. Say kill -l in your shell to see the valid signal names on your system.

Unrecognized switch: -%s  (-h will show valid options)
    (F) You specified an illegal option to Perl. Don't do that. (If you think you didn't do that, check the #! line to see if it's supplying the bad switch on your behalf.)

Unsuccessful %s on filename containing newline
    (W) A file operation was attempted on a filename, and that operation failed, PROBABLY because the filename contained a newline, PROBABLY because you forgot to chop() or chomp() it off. See the chomp entry in the perlfunc manpage.

Unsupported directory function
    (F) Your machine doesn't support opendir() and readdir().

Unsupported function fork
    (F) Your version of executable does not support forking.

    Note that under some systems, like OS/2, there may be different flavors of Perl executables, some of which may support fork, some not. Try changing the name you call Perl by to perl_, perl__, and so on.

Unsupported function %s
    (F) This machine doesn't implement the indicated function, apparently. At least, Configure doesn't think so.

Unsupported socket function
    (F) Your machine doesn't support the Berkeley socket mechanism, or at least that's what Configure thought.

Unterminated <> operator
    (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than".

Use of
    (D) Perl versions before 5.004 misinterpreted any type marker followed by "$" and a digit. For example, "$$0" was incorrectly taken to mean "${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004.

    However, the developers of Perl 5.004 could not fix this bug completely, because at least two widely-used modules depend on the old meaning of "$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the old (broken) way inside strings; but it generates this message as a warning. And in Perl 5.005, this special treatment will cease.

Use of $# is deprecated
    (D) This was an ill-advised attempt to emulate a poorly defined awk feature. Use an explicit printf() or sprintf() instead.

Use of $* is deprecated
    (D) This variable magically turned on multi-line pattern matching, both for you and for any luckless subroutine that you happen to call. You should use the new //m and //s modifiers now to do that without the dangerous action-at-a-distance effects of $*.

Use of %s in printf format not supported
    (F) You attempted to use a feature of printf that is accessible from only C. This usually means there's a better way to do it in Perl.

Use of bare << to mean <<"" is deprecated
    (D) You are now encouraged to use the explicitly quoted form if you wish to use an empty line as the terminator of the here-document.

Use of implicit split to @_ is deprecated
    (D) It makes a lot of work for the compiler when you clobber a subroutine's argument list, so it's better if you assign the results of a split() explicitly to an array (or list).

Use of inherited AUTOLOAD for non-method %s() is deprecated
    (D) As an (ahem) accidental feature, AUTOLOAD subroutines are looked up as methods (using the @ISA hierarchy) even when the subroutines to be autoloaded were called as plain functions (e.g. Foo::bar()), not as methods (e.g. Foo->bar() or $obj->bar()).

    This bug will be rectified in Perl 5.005, which will use method lookup only for methods' AUTOLOADs. However, there is a significant base of existing code that may be using the old behavior. So, as an interim step, Perl 5.004 issues an optional warning when non-methods use inherited AUTOLOADs.

    The simple rule is: Inheritance will not work when autoloading non-methods. The simple fix for old code is: In any module that used to depend on inheriting AUTOLOAD for non-methods from a base class named BaseClass, execute *AUTOLOAD = \&BaseClass::AUTOLOAD during startup.

    In code that currently says use AutoLoader; @ISA = qw(AutoLoader); you should remove AutoLoader from @ISA and change use AutoLoader; to use AutoLoader 'AUTOLOAD';.

Use of reserved word
    (D) The indicated bareword is a reserved word. Future versions of perl may use it as a keyword, so you're better off either explicitly quoting the word in a manner appropriate for its context of use, or using a different name altogether. The warning can be suppressed for subroutine names by either adding a & prefix, or using a package qualifier, e.g. &our(), or Foo::our().

Use of %s is deprecated
    (D) The construct indicated is no longer recommended for use, generally because there's a better way to do it, and also because the old way has bad side effects.

Use of uninitialized value
    (W) An undefined value was used as if it were already defined. It was interpreted as a "" or a 0, but maybe it was a mistake. To suppress this warning assign an initial value to your variables.

Useless use of
    (W) You did use re; without any arguments. That isn't very useful.

Useless use of %s in void context
    (W) You did something without a side effect in a context that does nothing with the return value, such as a statement that doesn't return a value from a block, or the left side of a scalar comma operator. Very often this points not to stupidity on your part, but a failure of Perl to parse your program the way you thought it would. For example, you'd get this if you mixed up your C precedence with Python precedence and said

        $one, $two = 1, 2;
    when you meant to say

        ($one, $two) = (1, 2);
    Another common error is to use ordinary parentheses to construct a list reference when you should be using square or curly brackets, for example, if you say

        $array = (1,2);
    when you should have said

        $array = [1,2];
    The square brackets explicitly turn a list value into a scalar value, while parentheses do not. So when a parenthesized list is evaluated in a scalar context, the comma is treated like C's comma operator, which throws away the left argument, which is not what you want. See the perlref manpage for more on this.

untie attempted while %d inner references still exist
    (W) A copy of the object returned from tie (or tied) was still valid when untie was called.

Value of %s can be
    (W) In a conditional expression, you used <HANDLE>, <*> (glob), each(), or readdir() as a boolean value. Each of these constructs can return a value of "0"; that would make the conditional expression false, which is probably not what you intended. When using these constructs in conditional expressions, test their values with the defined operator.

Variable
    (F) While "use strict" in effect, you referred to a global variable that you apparently thought was imported from another module, because something else of the same name (usually a subroutine) is exported by that module. It usually means you put the wrong funny character on the front of your variable.

Variable
    (W) An inner (nested) anonymous subroutine is inside a named subroutine, and outside that is another subroutine; and the anonymous (innermost) subroutine is referencing a lexical variable defined in the outermost subroutine. For example:

       sub outermost { my $a; sub middle { sub { $a } } }
    If the anonymous subroutine is called or referenced (directly or indirectly) from the outermost subroutine, it will share the variable as you would expect. But if the anonymous subroutine is called or referenced when the outermost subroutine is not active, it will see the value of the shared variable as it was before and during the *first* call to the outermost subroutine, which is probably not what you want.

    In these circumstances, it is usually best to make the middle subroutine anonymous, using the sub {} syntax. Perl has specific support for shared variables in nested anonymous subroutines; a named subroutine in between interferes with this feature.

Variable
    (W) An inner (nested) named subroutine is referencing a lexical variable defined in an outer subroutine.

    When the inner subroutine is called, it will probably see the value of the outer subroutine's variable as it was before and during the *first* call to the outer subroutine; in this case, after the first call to the outer subroutine is complete, the inner and outer subroutines will no longer share a common value for the variable. In other words, the variable will no longer be shared.

    Furthermore, if the outer subroutine is anonymous and references a lexical variable outside itself, then the outer and inner subroutines will never share the given variable.

    This problem can usually be solved by making the inner subroutine anonymous, using the sub {} syntax. When inner anonymous subs that reference variables in outer subroutines are called or referenced, they are automatically rebound to the current values of such variables.

Variable syntax
    (A) You've accidentally run your script through csh instead of Perl. Check the #! line, or manually feed your script into Perl yourself.

perl: warning: Setting locale failed.
    (S) The whole warning message will look something like:

            perl: warning: Setting locale failed.
            perl: warning: Please check that your locale settings:
                    LC_ALL = "En_US",
                    LANG = (unset)
                are supported and installed on your system.
            perl: warning: Falling back to the standard locale ("C").
    Exactly what were the failed locale settings varies. In the above the settings were that the LC_ALL was "En_US" and the LANG had no value. This error means that Perl detected that you and/or your system administrator have set up the so-called variable system but Perl could not use those settings. This was not dead serious, fortunately: there is a "default locale" called "C" that Perl can and will use, the script will be run. Before you really fix the problem, however, you will get the same error message each time you run Perl. How to really fix the problem can be found in the perllocale manpage section LOCALE PROBLEMS.

Warning: something's wrong
    (W) You passed warn() an empty string (the equivalent of warn "") or you called it with no args and $_ was empty.

Warning: unable to close filehandle %s properly
    (S) The implicit close() done by an open() got an error indication on the close(). This usually indicates your file system ran out of disk space.

Warning: Use of
    (S) You wrote a unary operator followed by something that looks like a binary operator that could also have been interpreted as a term or unary operator. For instance, if you know that the rand function has a default argument of 1.0, and you write

        rand + 5;
    you may THINK you wrote the same thing as

        rand() + 5;
    but in actual fact, you got

        rand(+5);
    So put in parentheses to say what you really mean.

Write on closed filehandle
    (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow.

X outside of string
    (F) You had a pack template that specified a relative position before the beginning of the string being unpacked. See the pack entry in the perlfunc manpage.

x outside of string
    (F) You had a pack template that specified a relative position after the end of the string being unpacked. See the pack entry in the perlfunc manpage.

Xsub
    (F) The use of an external subroutine as a sort comparison is not yet supported.

Xsub called in sort
    (F) The use of an external subroutine as a sort comparison is not yet supported.

You can't use -l on a filehandle
    (F) A filehandle represents an opened file, and when you opened the file it already went past any symlink you are presumably trying to look for. Use a filename instead.

YOU HAVEN'T DISABLED SET-ID SCRIPTS IN THE KERNEL YET!
    (F) And you probably never will, because you probably don't have the sources to your kernel, and your vendor probably doesn't give a rip about what you want. Your best bet is to use the wrapsuid script in the eg directory to put a setuid C wrapper around your script.

You need to quote
    (W) You assigned a bareword as a signal handler name. Unfortunately, you already have a subroutine of that name declared, which means that Perl 5 will try to call the subroutine when the assignment is executed, which is probably not what you want. (If it IS what you want, put an & in front.)

[gs]etsockopt() on closed fd
    (W) You tried to get or set a socket option on a closed socket. Did you forget to check the return value of your socket() call? See the getsockopt entry in the perlfunc manpage.

\1 better written as $1
    (W) Outside of patterns, backreferences live on as variables. The use of backslashes is grandfathered on the right-hand side of a substitution, but stylistically it's better to use the variable form because other Perl programmers will expect it, and it works better if there are more than 9 backreferences.

'|' and '<' may not both be specified on command line
    (F) An error peculiar to VMS. Perl does its own command line redirection, and found that STDIN was a pipe, and that you also tried to redirect STDIN using '<'. Only one STDIN stream to a customer, please.

'|' and '>' may not both be specified on command line
    (F) An error peculiar to VMS. Perl does its own command line redirection, and thinks you tried to redirect stdout both to a file and into a pipe to another command. You need to choose one or the other, though nothing's stopping you from piping into a program or Perl script which 'splits' output into two streams, such as

        open(OUT,">$ARGV[0]") or die "Can't write to $ARGV[0]: $!";
        while (<STDIN>) {
            print;
            print OUT;
        }
        close OUT;

Got an error from DosAllocMem
    (P) An error peculiar to OS/2. Most probably you're using an obsolete version of Perl, and this should not happen anyway.

Malformed PERLLIB_PREFIX
    (F) An error peculiar to OS/2. PERLLIB_PREFIX should be of the form

        prefix1;prefix2
    or

        prefix1 prefix2
    with nonempty prefix1 and prefix2. If prefix1 is indeed a prefix of a builtin library search path, prefix2 is substituted. The error may appear if components are not found, or are too long. See "PERLLIB_PREFIX" in README.os2.

PERL_SH_DIR too long
    (F) An error peculiar to OS/2. PERL_SH_DIR is the directory to find the sh-shell in. See "PERL_SH_DIR" in README.os2.

Process terminated by SIG%s
    (W) This is a standard message issued by OS/2 applications, while *nix applications die in silence. It is considered a feature of the OS/2 port. One can easily disable this by appropriate sighandlers, see the section on Signals in the perlipc manpage. See also "Process terminated by SIGTERM/SIGINT" in README.os2.