Search functionality stopped working in Windchill

[JR_14433142]

I am using Windchill PDMLink Release 11.2 and Datecode with CPS 11.2.1.5

The search function stopped working in Windchill. I was able to restore it by restarting the services on the server.
I would like a root cause as to why search stopped working and how to prevent it in the future.

Here are the errors that I faced
Status code: 501
Message: An unexpected error has occurred. Contact your system administrator for assistance.

[JR_14433142]

Attached logs.

[SWeiler_9940261]

Did you get the yellow banner that index search was not functioning? If so, it is likely that the problem was just that Solr service had stopped.