I'm dealing with this issue on a system where we were having problems moving a project from 7.3 to 8.1.x. Support was able to create a backup for us and we restored to a new server running 8.1.30 (new server to test before commissioning).
I restored everything disabled and was systematically testing each component. The database connection wasn't working because of TLS so I adjusted a config file to disable TLS and tried to restart the Ignition service. It won't start now.
I tried the step outlined in this thread of deleting jre-win and letting the it rebuild jre-win and it is not working.
I'm interested in any ideas you may have.