UserHost.exe error messages on our unattended bot

Hello - Today I found the errors below when I logged to our production windows server hosting a couple unattended robots, all related to UserHost.exe:

Has anyone seen this before and know what they are about? since seeing these errors, we got a “Could not connect to UIPath Robot Service” message on the robot tray and were only able to resolve by rebooting the server.

Any guesses on what may be the issue?