You are viewing the version of this documentation from Perl 5.37.6. This is a development version of Perl.



perldelta - what is new for perl v5.37.6


This document describes differences between the 5.37.5 release and the 5.37.6 release.

If you are upgrading from an earlier release such as 5.37.4, first read perl5375delta, which describes differences between 5.37.4 and 5.37.5.

Incompatible Changes


Starting in this release, if the input string is undef, it remains undef. Previously it would be changed into a defined, zero-length string.

Modules and Pragmata

New Modules and Pragmata

Updated Modules and Pragmata


Changes to Existing Documentation

We have attempted to update the documentation to reflect the changes listed in this document. If you find any we have missed, open an issue at


The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see perldiag.

New Diagnostics

New Errors


New Warnings


Changes to Existing Diagnostics

Utility Changes



Configuration and Compilation


Platform Support


stat() now works on AF_UNIX socket files. [github #20204]

readlink() now returns the PrintName from a symbolic link reparse point instead of the SubstituteName, which should make it better match the name the link was created with. [github #20271]

Internal Changes

-=head1 Selected Bug Fixes

Known Problems


Errata From Previous Releases



Perl 5.37.6 represents approximately 4 weeks of development since Perl 5.37.5 and contains approximately 16,000 lines of changes across 230 files from 26 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 12,000 lines of changes to 130 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.37.6:

Alexander Nikolov, Andreas König, Aristotle Pagaltzis, Bram, Branislav Zahradník, chromatic, David Mitchell, E. Choroba, Elvin Aslanov, Felipe Gasper, Graham Knop, James E Keenan, Joe McMahon, Johan Vromans, Karl Williamson, Leon Timmermans, Mattia Barbon, Max Maischein, Paul Evans, Ricardo Signes, Richard Leach, TAKAI Kousuke, Todd Rinaldo, Tom Stellard, Tony Cook, Yves Orton.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the perl bug database at There may also be information at, the Perl Home Page.

If you believe you have an unreported bug, please open an issue at Be sure to trim your bug down to a tiny but sufficient test case.

If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.

Give Thanks

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the perlthanks program:


This will send an email to the Perl 5 Porters list with your show of thanks.


The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.