Before the PGP Desktop enrollment starts a certificate warning is shown or a client connected to the PGP Universal web services is getting a certificate warning.
PGP Desktop shows the following warning:
"Server keys.xy-corp.com presented a TLS certificate that was issued by an unknown Certificate Authority: ........."
The problem is the Entrust Certification Authority - L1C certificate is not by default integrated into PGP Universal server, up to version 3.2 MP4.
The solution is to import the "Entrust Certification Authority - L1C" certificate to Keys/Trusted Keys on the PGP Universal server. In the next step the interface certificate needs to be first un-assigned or set to none and after a services restart re-assigned to the interface.
The Entrust Certification Authority - L1C certificate will be by default integrated into a later version of PGP Universal.