Here’s what to do when you receive the following error:

sp_dbhelp2

Description:

This indicates a problem with your SQL Server installation. At least one of the databases on your database server
has a missing or corrupt owner. The system stored procedure “sp_helpdb”, which lists your existing databases,
requires a valid owner for every database in order to run.

To see what’s happening, open Query Analyzer and run: exec sp_helpdb. You will see an error message like the one above.

Common Cause:

Outside of SQL Server, the database owner’s Windows account gets deleted. This sours things within SQL Server, it orphans that database.

Solution:

Following is the response I’ve seen two Microsoft reps post on groups.  <dbname> is the database with the missing or corrupt owner.

1)
Use <dbname>
exec sp_changedbowner ‘[new user not in db already]
–this will work & sp_helpdb will execute correctly

2) Then execute the same query using sa & it will work:

Use <dbname>
exec sp_changedbowner ‘sa’
–The dependent aliases were mapped to the new database owner. Database owner changed.

Of course, you may not know which database has the problematic owner. Here’s from a Microsoft Rep (view thread):

The database owner SID will become invalid if the owner’s Windows account is
deleted.  This causes problems with sp_helpdb because of the NULL account
name returned from SUSER_SNAME()..  You can identify these problem databases
with the script below and correct the problem by executing sp_changedbowner
with a valid login.

SELECT name
FROM master..sysdatabases
WHERE SUSER_SNAME(sid) IS NULL