I ran into this issue with OSX.
Original answer:
It seems like a gpg update (of brew) changed to location of gpg to gpg1, you can change the binary where git looks up the gpg:
git config --global gpg.program gpg1
If you don’t have gpg1: brew install gpg1.
Updated answer:
It looks like gpg1 is being deprecated/“gently nudged out of usage”, so you probably should actually update to gpg2, unfortunately this involves quite a few more steps/a bit of time:
brew upgrade gnupg # This has a make step which takes a while brew link --overwrite gnupg brew install pinentry-mac
on old homebrew:
echo "pinentry-program /usr/local/bin/pinentry-mac" >> ~/.gnupg/gpg-agent.conf killall gpg-agent
On more rencent one like M1 macs:
echo "pinentry-program /opt/homebrew/bin/pinentry-mac" >> ~/.gnupg/gpg-agent.conf killall gpg-agent
The first part installs gpg2, and latter is a hack required to use it. For troubleshooting, see this answer (though that is about linux not brew), it suggests a good test:
echo "test" | gpg --clearsign # on linux it's gpg2 but brew stays as gpg
If this test is successful (no error/output includes PGP signature), you have successfully updated to the latest gpg version.
You should now be able to use git signing again!
It’s worth noting you’ll need to have:
git config --global gpg.program gpg # perhaps you had this already? On linux maybe gpg2 git config --global commit.gpgsign true # if you want to sign every commit
Note: After you’ve ran a signed commit, you can verify it signed with:
git log --show-signature -1
which will include gpg info for the last commit.