MSSQL Error 'The underlying provider failed on Open'

Question

I was using an .mdf for connecting to a database and entityClient. Now I want to change the connection string so that there will be no

Answer 1

I was searching all over the web for this problem. I had the wrong name in the connection string, please check you connection string in web.config. I had name="AppTest" but it should have been name="App".

In my AppTestContext.cs file I had:

public AppTestContext() : this("App") { }

Wrong connection string:

Right connection string: