I did an upgrade from YT5.x to 6 and all went well. Chose the upgrade path and everything converted nicely and I was able to login to the new version.
However, if I restart the YT service or the machine the YT service will not start. I find it weird it launches correctly after the installation has finished but can't manage a restart.
From the service.log I get the following error:
Failed to start the application: Failed to start JetBrains YouTrack 6.0: Not allowed exit code -1 from process: bin/youtrack configure
I logon to the service as: .\JetBrainsYouTrack user.
I have attached some logs for your aid.