I've run across this issue twice while upgrading 2012 R2 standalone VMM servers. In the first instance we just rebuilt the VMM server, but since it has resurfaced, I'm curious if there are any suggestions to better troubleshoot.
Pre-upgrade:
Windows Server 2012 R2
SCVMM 2012 Update Rollup 14
SQL server 2014
Post-upgrade:
Windows Server 2019 1809
SCVMM 2016 Update Rollup 8
SQL server 2016
The upgrade process for standalone servers was followed (can't include a link here but it's the Microsoft documented process last updated 3/13/19) with the only exception being Server 2019 installed in place of 2016 for our operating system.
After starting the VMM service, it runs fine for anywhere between 6 hours and several days, at which point it hangs. The service is still reported as running and no logs are generated, but all console and all other application connections time out. Restarting the VMM service (or the entire VM) restores connectivity.
I'm hesitant to enable debug logging due to how long the trace may need to run to catch whatever is dying, but I'm thinking this might be the best option. All SQL, Windows Server, and other patches are in place.