Issue

When you try to access Database Diagrams folder in SQL Server 2005 Management Studio for a database that was restored from a backup made in SQL2000 you may get the following error:

“Database diagram support objects cannot be installed because this database does not have a valid owner. To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, then add the database diagram support objects.”

This means that “database diagram support” could not be installed due to the database compatibility mode.

Workaround

In order to solve this issue you should change the compatibility mode to level 2005, install database diagram support, and then return the desired compatibility level.

Steps:

1. Open Database Properties dialog box
2. Open the Options Page
3. Change the Database Compatibility Level to “SQL Server 2005”
4. Open Database Diagrams Folder and click “yes” in the Dialog Box asking for the installation of Database Diagram Support Objects
5. Return to the desired compatibility level, following steps 1-3