Have you ever had this error?
$ git co -t origin/branch-name warning: refname 'origin/branch-name' is ambiguous. warning: refname 'origin/branch-name' is ambiguous. fatal: Ambiguous object name: 'origin/branch-name'.
Well, as it turns out the issue was caused by a typo when I first attempted to check out the "branch-name" branch:
$ git co -b origin/branch-name
When this happened, it created the file .git/refs/heads/origin/branch-name. So, I just deleted the file:
$ rm .git/refs/heads/origin/branch-name
Then, attempted to check out the branch again:
$ git co -t origin/branch-name Branch branch-name set up to track remote branch branch-name from origin. Switched to a new branch 'branch-name'
And it works! Hopefully, this helps someone (or even me if I forget)!