Add a Changelog (best named 'Changes') to the distribution. It should list at least major changes implemented in newer versions.
Add a section called "LICENSE" to the documentation, or add a file named LICENSE to the distribution.
Add =head1 LICENSE and the text of the license to the main module in your code.
Add a MANIFEST to the distribution. Your buildtool should be able to autogenerate it (eg "make manifest" or "./Build manifest")
Add a META.yml to the distribution. Your buildtool should be able to autogenerate it.
Run a proper command ("make manifest" or "./Build manifest", maybe with a force option), or use a distribution builder to generate the MANIFEST. Or update MANIFEST manually.
Error: Cannot find MANIFEST in dist.
List all used modules in META.yml requires
Add =head1 LICENSE and/or the proper text of the well-known license to the main module in your code.
Add a META.json to the distribution. Your buildtool should be able to autogenerate it.
Define the license if you are using in Build.PL. If you are using MakeMaker (Makefile.PL) you should upgrade to ExtUtils::MakeMaker version 6.31.
Add 'use warnings' (or its equivalents) to all modules (this will require perl > 5.6), or convince us that your favorite module is well-known enough and people can easily see the modules warn when something bad happens.
This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.