DB cannot be opened because it is version 655. This server supports version 612

Turns out that deinstalling SQL Express and reinstall the latest version fixed the problem. I chose SQLSERVER2008 as Instance-Name while installing and set it in Visual Studio as described above.

Go to the Services control panel and look for a service named SQL Server (XXX) -- that XXX is the name of the instance that service is running. You just have to find the 2008R2 instance that you installed and type that into the "SQL Server Instance Name" box.

Might help to try to change the compatibility level, to make sure its backwards compatible.

Verify what level it is

USE VJ_DATABASE;
GO
SELECT compatibility_level
FROM sys.databases WHERE name = 'VJ_DATABASE';
GO

Then make it compatible with the older version

ALTER DATABASE VJ_DATABASE
SET COMPATIBILITY_LEVEL = 110;   
GO

• 100 = Sql Server 2008
• 110 = Sql Server 2012
• 120 = Sql Server 2014

By default, Sql Server 2014 will change the db versions compatibility to only 2014, using the @@ version you should be able to tell, which version Sql Server is.

Then run the command above to change it the version you have.

Additional step: Ensure you look at the accessibility of the DB is not reset, do this by right clicking on properties of the folder and the database. (make sure you have rights so you don't get an access denied)