Sign the dist as the last step before creating the archive. Take care not to modify/regenerate dist meta files or the manifest.

Error: Old SIGNATURE detected. Please inform the module author to regenerate SIGNATURE using Module::Signature version 0.82 or newer. gpg: Signature made Tue 02 Jun 2009 04:54:16 AM JST gpg: using DSA key 58CA219610F54327 gpg: Can't check signature: No public key ==> BAD/TAMPERED signature detected! <==

Add a META.json to the distribution. Your buildtool should be able to autogenerate it.

This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.