PAR 1.010 Latest
Take a look at the META.yml Spec at http://module-build.sourceforge.net/META-spec-v1.4.html (for version 1.4) or http://search.cpan.org/perldoc?CPAN::Meta::Spec (for version 2), and change your META.yml accordingly.
Error: 'Module::Signature' for 'Digest' is not a valid version. (recommends -> Digest) [Validation: 1.4]
Add 'use strict' (or its equivalents) to all modules, or convince us that your favorite module is well-known enough and people can easily see the modules are strictly written.
Split the distribution, or fix the version numbers to make them consistent (use the highest version number to avoid version downgrade).
Add a META.json to the distribution. Your buildtool should be able to autogenerate it.
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.