SQL Server 2005 ‘Login failed’ (error 18456 state 16)

The event log of one of our SQL Servers filled up with events 18456 (every minute).

Failure Audit: Login failed for user '<DOMAIN>\<username>’. [CLIENT: <local machine>]

Looking in the SQL Server log, I found some extra information.

2011-10-18 12:52:00.55 Logon       Error: 18456, Severity: 14, State: 16.

I found this MSDN blog post, explaining most of the State codes, except for state 16.

ERROR STATE	ERROR DESCRIPTION
2 and 5	Invalid userid
6	Attempt to use a Windows login name with SQL Authentication
7	Login disabled and password mismatch
8	Password mismatch
9	Invalid password
11 and 12	Valid login but server access failure
13	SQL Server service paused
18	Change password required

 

Digging a little further, I found that State 16 usually means that the target database cannot be located. I most cases, this is due to an SQL Server Job that targets a deleted of offline database.

 

Deleting or disabling the job gets rid of the errors in the event log.