- What’s the failure message?
- Did you check in the other, working project that there’s no “user key” set in the “Checkout SSH keys” setting?
- What’s the output of
ssh -vT git@bitbucket.org?
In the failing project, did you manually configure the key via circle.yml: private key (from environment variable or “SSH permissions”) and saved to ${HOME}/.ssh? Then you should head over to another post which reports the same issue, I guess.