foobared
Nov 17 16:28:14 puppetmaster2003 puppet-master[10959]: On the agent:
Nov 17 16:28:14 puppetmaster2003 puppet-master[10959]:   1a. On most platforms: find /var/lib/puppet/server/ssl -name puppet.pem -delete
Nov 17 16:28:14 puppetmaster2003 puppet-master[10959]:   1b. On Windows: del "\var\lib\puppet\server\ssl\certs\puppet.pem" /f
Nov 17 16:28:14 puppetmaster2003 puppet-master[10959]:   2. puppet agent -t
Nov 17 16:28:18 puppetmaster2003 systemd[1]: Started Session c365144 of user gitpuppet.
Nov 17 16:28:18 puppetmaster2003 systemd[1]: session-c365144.scope: Succeeded.
Nov 17 16:28:28 puppetmaster2003 puppet-agent[11030]: Disabling Puppet.
Nov 17 16:28:36 puppetmaster2003 systemd[1]: Started Session 417460 of user jbond.

check files
puppetmaster2003 ~ % sudo find /var/lib/puppet/server/ssl/ -name puppet.pem -ls                                                                                         [16:28:50]
  1315220      4 -rw-r--r--   1 puppet   puppet       1582 Jan 20  2020 /var/lib/puppet/server/ssl/certificate_requests/puppet.pem
  1315213      4 -rw-r--r--   1 puppet   puppet        800 Nov 17 15:28 /var/lib/puppet/server/ssl/public_keys/puppet.pem
  1315212      4 -rw-r-----   1 puppet   puppet       3243 Nov 17 15:28 /var/lib/puppet/server/ssl/private_keys/puppet.pem


# stop apache; delete files
puppetmaster2003 ~ % sudo systemctl stop apache2
puppetmaster2003 ~ % sudo find /var/lib/puppet/server/ssl/ -name puppet.pem -delete                                                                                     
puppetmaster2003 ~ % sudo find /var/lib/puppet/server/ssl/ -name puppet.pem -ls                                                                                        
puppetmaster2003 ~ %  


# start apache
Nov 17 16:31:28 puppetmaster2003 puppet-master[11940]: Starting Puppet master version 5.5.10
puppetmaster2003 ~ % sudo find /var/lib/puppet/server/ssl/ -name puppet.pem -ls                                                                                         [16:31:28]
  1315213      4 -rw-r--r--   1 puppet   puppet       1582 Nov 17 16:31 /var/lib/puppet/server/ssl/certificate_requests/puppet.pem
  1315212      4 -rw-r--r--   1 puppet   puppet        800 Nov 17 16:31 /var/lib/puppet/server/ssl/public_keys/puppet.pem
  1314808      4 -rw-r-----   1 puppet   puppet       3243 Nov 17 16:31 /var/lib/puppet/server/ssl/private_keys/puppet.pem