Login failed for user '(null)'

I get the following error in the SQL Logs.

What does this error mean and how can I resolve this?

18452 :
Login failed for user '(null)'. Reason: Not associated with a trusted SQL Se
rver connection.

Thanks

Santhosh

Some client tries to login to SQL Server without passing the WIndows credentials.

HTH, Jens K. Suessmeyer.

http://www.sqlserver2005.de|||

How can I resolve this?

The scenario is... We use a third party backup software. This backup software uses SQL as its database to store session records. Whenever, the tape engine starts it logs on the above message and also during the backups it logs on the above message.

While configuring SQL to be as the backup software's database, there is a option to enter SQL Security. When we enter SA as security, we do not get this error. When we use windows security, we get this error.

Any help is appreciated.

Thanks

Santhosh

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Check the KBAs

http://support.microsoft.com/kb/265808

http://support.microsoft.com/kb/555332

And http://blogs.msdn.com/sql_protocols/archive/2005/09/28/474698.aspx if its a SQL 2005 box.

As suggested you have to check and configure the SQL Server authentication to allow this backup software to connect to database.

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Is the backup software running on the same machine as SQL Server? If not, are the machines in the same domain?

Thanks
Laurentiu

sql