- Follow https://www.git-tower.com/help/guides/integration/gpg/mac
- If everything fails, use
GIT_TRACE=1prefixed to the git commit command to try and see what git is actually doing
- Key might have expired, run the GPG Keychain application to check, it offers to extend the key.
- You must then export the new key, delete the expired key in your GitHub account, and upload the new key to GitHub. Unverified past commits then become verified.
There is one post tagged gpg.