We find that the DefaultAppPool process, under Application Pools in IIS Manager, keeps stopping about once every day and has to be manually restarted. When the pool is in the stopped state, we are unable to run or edit custom reports.
The Event Logs show messages like this:
Exception code 0xc0000374
Release : 21.2
Component : NQRACO - NETQOS RA CONSOLE
The DefaultAppPool crashes were related to scans from a 3rd-party utility called Nessus
Found that the DefaultAppPool problems were related to Nessus scans. After stopping the Nessus scans, the Application Pool remained active.
See also the following Microsoft article: