For what it's worth, I had that same error message (OS X), and I managed to fix it. After using homebrew to make sure my git was up-to-date and gpg was also installed correctly, I told git where gpg is (for some reason, despite being in my PATH, it wasn't registering?):
git config --global gpg.program /usr/local/bin/gpg
After that, I had to make a tweak to gpg so I didn't get another annoying error. In ~/.gnupg/gpg.conf, adding 'no-tty' got everything working smoothly.
I agree that that was way too tedious, but it did work out. :)
> There is no UI that allows you to specify that you want the merge commit to be signed.
Ah ok, I see what you mean. I don't think theres a way to have rebase re-sign things inside SourceTree either, I run in to that one constantly and have to open a terminal.
And if you configure git to sign all commits, you get this error:
https://confluence.atlassian.com/sourcetreekb/sourcetree-com...