Troubleshooting - 'Sev. 14 Errors' - Login failed for user 'NT AUTHORITY\SYSTEM'
Sometimes your SQL Error log might fill up with the error "Sev. 14 Errors – Login failed for user 'NT AUTHORITY\SYSTEM'. [CLIENT : Local System ]"
This happens when user 'NT AUTHORITY\SYSTEM' local group does not have access to SQL Server and some service is trying to access SQL Server using this account.
To Trace out which services is causing this issue, first you will have to run the profiler. We do not require all the events, so we can apply the filter for profiler to capture only "Audit Login Failed" event class.
Continue to Read here for more information.