How to clear git caches?

Use git fetch -p to prune your local caches

I had a weird issue on macOS where I would get phantom Uppercase versions of branches, e.g. my remote branch listing would show Ben/some-branch locally, but the server would show ben/some-branch.

git remote prune origin would (correctly) remove them, but git fetch --prune would (incorrectly) bring them right back. Very weird.

Best I can tell, at some point in the past, I had a Ben/something branch, but because the default macOS filesystem is case-insensitive, the .git metadata was hanging onto a (capitalized) .git/refs/remotes/origin/Ben folder and using it for the (lowercase) remote branch refs.

rm -rf .git/refs/remotes/origin/Ben && git fetch put me back in order.

Like mentioned on cleaning up old remote git branches, you should use git remote prune origin.

I didn't use the other two commands mentioned there.