Error: 18456, Severity: 14, State: 16

After working on of my clients we started noticing that for some mysterious reason our SQL logs were getting massive. As well Microsoft SQL 2005 has been reporting “login failed” errors for sometime. After examining the SQL log file viewer I discovered an error, actually two, reoccurring in succession every minute in the SQL server log!

After examining this descriptive error I started wondering how the can “NT Authority\System” be denied access! Naturally, I started checking all the permissions for the service account and even trying other accounts. I had no luck everything looked correct.

However, I noticed that in the log for the SQL Agent it too is logging errors in the same fashion. After examining the SQL Agent Jobs I found a ASPState_Job_DeleteExpiredSessions job which is used to track sessions from ASP.NET applications (see .Net Session State for more information on sessions states). If your reading this for help you will want to thoroughly investigate your web.config and have a good understanding of the ASP application before proceeding!  In my instance the job must have been create by another SQL instance or on accident. My ASP application uses “InProc” session state management so I don’t even need it. I simply disabled the job and poof the errors are no more!

Other ASP applications may require that you use the aspnet_regsql.exe to remove it properly. I hope this helps you find your way!