Visual Studio Throws an Error When Trying to Connect/Open an .mdf File


Problem: You try to open a .mdf file in visual studio and you get one of the following errors.

Connections to SQL Server files (*.mdf) require SQL Server Express 2005 to function properly.  Please verify the installation of the component or download from the URL:

Failed to generate a user instance of SQL Server due to a failure in starting the process for the user instance. The connection will be closed.

Solution: Open Server Explorer add Data Connection. Make sure the Data Source = Microsoft SQL Server Database File (SqlClient) and browse to the .mdf file located in your source directory(There maybe on located in the bin directory but this will get copied over by what is in src on a build). Click the Advance button. In order to work I needed to switch the Data Source to .\SQLEXPRESS2005 (This will be different for each computer).

Final connection string should look something like this:

Data Source=.\SQLEXPRESS2005;AttachDbFilename=|DataDirectory|\NerdDinner.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True