I restored a DB but it does not allow me to create a Database Diagram

Question

I am using SQL Server Management Studio (version 18.12.1) and just restored a database not created by me, and when I try to create a DB diagram I get an error like this:

Cannot execute as thee database principal because the principal "dbo" does not exist, this type of principal cannot be impersonated, or you do not have permission, (Microsoft SqlServer Error: 15517)

The database is Microsoft SQL Server Express version 15.0.4153.1

If I create a database from scratch I can create db diagrams!!! But not with these other databases... what can I do to fix this?

Answer 1

This is due to that the SID for the dbo inside the database does not match the owner_sid in sys.databases.

A simple way out is to change the database owner:

   ALTER AUTHORIZATION ON DATABASE::YourDB TO YourDomain\YourUser