Add compute environment: Unexpected error while processing request

I’m trying to add my k8s server but getting the below rather unhelpful error:
Unexpected error while processing request - Error ID: 5560g3u9aSyER6cEhWcFI4

There doesnt seem to be anywhere to get any more detail on the error.

I’m curious if it is related to the SSL certificate question when registering the cluster - does it mean the clusters cert - or when one that our nginx proxy serves up which is secured with lets encrypt.