LocalSqlServer was not found in the applications configuration or the connection string is empty

Question

I've just upgraded a .NET 3.5 MVC 1 project to .NET 4.0 MVC 3 and for some reason now when I try to run it it says:

The connection name 'LocalSqlServer' was not found in the applications configuration or the connection string is empty.`

I'm not sure why it does this as no where in my code does it look for a LocalSqlServer connection string, and if I put in a LocalSqlServer connection string in my config file with the value of my standard connection string and try to go onto the website, it takes me to the 'please log in' URL but with a 404 page (and not the custom 404 page either)

Anyone know what the problem could be?

Regards,
Harry

Answer 1

The LocalSqlServer connection string is defined in your Machine.config.

If you don't have a default Machine.config file, it might have been removed. You would then need to re-add it inside your own Web.config.

My LocalSqlServer:

<add name="LocalSqlServer" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>

You can find your machine.config here:

C:\Windows\Microsoft.NET\Framework\[FRAMEWORK VERSION]\CONFIG\machine.config

Answer 2

I have been tracking this same issue on a local application. When I had started working on it, the application was running ASP.NET Framework version 4.5. In the past, it had implemented structures from namespace System.Web.Providers. We updated the code to no longer use these classes and removed their references in the Web.config but we still received this error.

What I determined was the System.Web.Providers.dll was still present within the bin directory. We removed the reference before we performed a Clean or Rebuild, so the Clean or Rebuild action never removed it. (Note: It also never cleaned other files from references we removed before the Clean/Rebuild.) After deleting the files from the corresponding application bin directory, the application no longer threw the exception related to LocalSqlServer.