gpg failed to sign the data fatal: failed to write commit object [Git 2.10.0]

Question

I followed few articles over the pretty attributes on Git 2.10 release note. Going through which upgraded the git to 2.10.0 and made changes to global .gitconfig

Answer 1

If everything fails, use GIT_TRACE=1 to try and see what git is actually doing:

$ GIT_TRACE=1 git commit -m "Add page that always requires a logged-in user"
20:52:58.902766 git.c:328               trace: built-in: git 'commit' '-vvv' '-m' 'Add page that always requires a logged-in user'
20:52:58.918467 run-command.c:626       trace: run_command: 'gpg' '--status-fd=2' '-bsau' '23810377252EF4C2'
error: gpg failed to sign the data
fatal: failed to write commit object

Now run the failing command manually:

$ gpg -bsau 23810377252EF4C2
gpg: skipped "23810377252EF4C2": Unusable secret key
gpg: signing failed: Unusable secret key

Turns out, my key was expired, git was not to blame.