Maybe this thread can help. At least the same exception is reported. Maybe you are using a proxy too. If so, this might also be helpful Configure Proxy - SNAP
When trying to access the SNAP plugins (or updates) I receive the following error:
Unable to connect to the SNAP Supported Plugins because of PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
Check your proxy settings or try again later. The server may be unavailable at the moment.
You may also want to make sure that your firewall is not blocking network traffic.
I believe this is due to a cert…