puppet cert list -all: Error: header too long

I tried restarting my puppet master but the error still persists.

Also see it from all the puppet agents that try to join.

puppet agent --server puppet.example.com --waitforcert 60 --test --verbose
Error: Could not request certificate: Error 400 on SERVER: header too long

Solution 1:

There were empty ca request files on the puppet master server that needed to be removed.

here: /var/lib/puppet/ssl/ca/requests