/.git/shallow.lock file exists error when deploy to Heroku

Yesterday we had an error when application deployed to Heroku and the build process restarted. Since all build processes fail with the next message:

Warning: Permanently added the RSA host key for IP address '' to the list of known hosts.
fatal: Unable to create '/home/ubuntu/reactor/.git/shallow.lock': File exists.
If no other git process is currently running, this probably means a
git process crashed in this repository earlier. Make sure no other git
[[ ! -s "$(git rev-parse --git-dir)/shallow" ]] || git fetch --unshallow returned exit code 128
process is running and remove the file manually to continue. Action failed: Fetch full repo

I’m trying to delete the shallow.lock via ssh, but the problem persists. How we resolve that?

Thank you for the help!