Today I ran into this error while trying to update Homebrew.
I thought it might be an issue with Homebrew itself, but running
brew doctor seemed to indicate that everything was working correctly. I know Homebrew uses a git repo (which is pretty obvious from the error message) so I thought that the git repo or git itself might be the problem. You can navigate to the repo by doing
cd $(brew --repo).
After plenty of trail and error I finally found someone who had the same problem. It appears that this is a problem if you’re trying to authenticate with https but you have 2FA enabled. This can be solved by forcing git to use ssh for all interactions.
This will use your keys in
~/.ssh - if you’re struggling with that part you can follow along in the github tutorial.
What would I have done without the internet?