Problems with puppet ca


We are in progress of deploying a puppet solution

we keep getting this about the puppet ca:
Failure: ERF50-5345 [Foreman::WrappedException]: Unable to connect ([ProxyAPI::ProxyException]: ERF12-5356 [ProxyAPI::ProxyException]: Unable to get PuppetCA certificates ([RestClient::NotAcceptable]: 406 Not Acceptable) for proxy https://fqdn:8443/puppet/ca)

i have no idea what this error means and what we can do to fix it?