Login failed. The login is from an untrusted domain and cannot be used with Windows authentication. (SQL Server 18452)

Another day, another weird error made my day. The day went like this

I had my breakfast and immediately got call from office stating something went down and the world is ending and need someone to save it. You know as always I took the responsibility of saving the world again and ended up spending 8hrs continuously on conference call and figuring out, it got nothing to do with SQL database.

Issue: Application went down and when the application team verifying logs they keep receiving below error:

Login failed. The login is from an untrusted domain and cannot be used with Windows authentication. (SQL Server 18452)

There are many reasons why we face this error, it’s not a single bolt that needs to be tightened to fix it. In most of cases when you are facing this issue the basic stuff to verify from SQL side:

Login has appropriate permissions to the DB.

Verify if any other user from same domain can access the server.

Try verifying connection with SQL login.

In my case when we changed the application service to run with SQL user it worked fine but with domain account the application service not starting up. The domain account has all required SQL permissions but when verified found that not able to connect to the machine with the domain account.

Tried with other user of same domain and same issue for other user as well, so confirmed domain issue. Domain team verified and found that one of Active Directory domain controller got rebooted during the weekend after a patch installation. Later on it’s found that the patch MS15-027 has been installed during weekend and that has led to the issue. 

After un-installing the patch, the application came up fine with domain account as well.

As mentioned previously, this is a very generic error and reason could be anything. I don’t advise to perform this un-installation unless you are sure it will fix it and after effects of it.

Thanks