Earlier I wrote a blog post about how to resolve the error with database diagram. Today I faced the same error when I was dealing with a database which is upgraded from SQL Server 2005 to SQL Server 2008 R2. When I was searching for the solution online I ended up on my own earlier solution SQL SERVER – ERROR: FIX – Database diagram support objects cannot be installed because this database does not have a valid owner.
I really found it interesting that I ended up on my own solution. However, the solution to the problem this time was a bit different. Let us see how we can resolve the same.
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.
Workaround / Fix / Solution :
Follow the steps listed below and it should for sure solve your problem. (NOTE: Please try this for the databases upgraded from previous version. For everybody else you should just follow the steps mentioned here.)
This will solve your problem. However, there is one very important note you must consider. When you change any database owner, there are always security related implications. I suggest you check your security policies before changing authorization. I did this to quickly solve my problem on my development server. If you are on production server, you may open yourself to potential security compromise.
Reference: Pinal Dave (http://blog.sqlauthority.com)