puppet agent -t
Info: Not using expired certificate for ca from cache; expired at Tue Apr 07 23:15:43 UTC 2020
Info: Not using expired certificate for ca from cache; expired at Tue Apr 07 23:15:43 UTC 2020
Info: Not using expired certificate for ca from cache; expired at Tue Apr 07 23:15:43 UTC 2020
Error: Could not request certificate: stack level too deep
Exiting; failed to retrieve certificate and waitforcert is disabled
Foreman 1.12 has been EOL for several years by now. The currently supported versions are 1.24 and 2.0. It is very unlikely many people have a working 1.12 environment and can assist you with the exact commands needed to fix this issue. I would highly recommend upgrading to newer supported versions (btw, puppet 3 is also long EOL by now).