Delete .mdf file from app_data causes exception cannot attach the file as database

Question

I am building a web application using VS 2012 MVC4 code first. In order to recreate the .mdf file after I changed the model, I manually deleted the file from the app_data directory in VS. I have done this a few times before without any problem.

Now I receive an exception:

The underlying provider failed on Open. ==> Cannot attach the file MYDB.mdf as database 'MYDB'.

I will appreciate your help on how to recreate the .mdf file.

Thank you!

Answer 1

That what fixed it for me, From Package Manager Console run these commands:

  sqllocaldb.exe stop v11.0   sqllocaldb.exe delete v11.0 

And then:

  Update-Database 

Answer 2

Use SQL Server Object Explorer to delete the database rather than just deleting the .mdf file in Solution Explorer. Otherwise the SQL Server instance still thinks the database name is used and the next time you try to attach a database to the same name it won't work. See the section on Initial Catalog in this MSDN page:

http://msdn.microsoft.com/en-us/library/jj653752.aspx#initialcatalog