When this error appears, it typically means that the ssh keys have not been configured in all locations. SSH keys will need to be set in both the project setting's page and within the config.yml:
- Add deploy key here in the new UI:
https://app.circleci.com/settings/project/github/<your organization name>/<project name>/ssh
- Old UI here:
- In the config.yml, add the fingerprint using the
More information on configuring ssh keys can be found in the GitHub and Bitbucket Integration documentation.