After I have installed SQL Server 2008 Developer edition, I wanted to add a local database file (.mdf), but I received an error which said that I need to install the SQL Server Express version back.
As I still had the Express version installed, I went to services and started the SQL Server Express process. This was not enough.
After many hours I have found the solution. I had to change the SQL default instance in Visual Studio.
Go to Tools -> Options -> Database Tools -> Data Connections -> change the SQL Server Instance Name to “SQLEXPRESS“.
Note: In order to work, you also have to start the service from Control Panel.
UPDATE: The error that I’ve received when I tried to add the SQL Local Database File(.mdf) is the following:
Connections to SQL Server Database files (.mdf) require SQL Server 2005 Express or SQL Server 2008 Express to be installed and running on the local computer. The current version of SQL Server Express can be downloaded at the following URL:…