Puppet Cert problem

Problem:

puppet agent --test returns

[root@host ~]# puppet agent --test
Warning: Unable to fetch my node definition, but the agent run will continue:
Warning: SSL_connect returned=1 errno=0 state=error: certificate verify failed: [self signed certificate in certificate chain for /CN=Puppet Root CA: a441f9721f4df7]
Info: Retrieving pluginfacts
Error: /File[/var/lib/puppet/facts.d]: Failed to generate additional resources using 'eval_generate': SSL_connect returned=1 errno=0 state=error: certificate verify failed: [self signed certificate in certificate chain for /CN=Puppet Root CA: a441f9721f4df7]
Error: /File[/var/lib/puppet/facts.d]: Could not evaluate: Could not retrieve file metadata for puppet://proxy.example.org/pluginfacts: SSL_connect returned=1 errno=0 state=error: certificate verify failed: [self signed certificate in certificate chain for /CN=Puppet Root CA: a441f9721f4df7]
Wrapped exception:
SSL_connect returned=1 errno=0 state=error: certificate verify failed: [self signed certificate in certificate chain for /CN=Puppet Root CA: a441f9721f4df7]

Expected outcome:

Running puppet agent

Foreman and Proxy versions:

1.24.3

Foreman and Proxy plugin versions:

Distribution and version:

CentOS 7

This worked before. But obviously there is a problem with the self-signed cert? How can I check or fix this?

Are you by any chance using a puppet 5 client while connecting to a puppet 6 server?