VS 2008, .net 3.5 project in VS 2010: Failed to load type ... EntityDesignerBuildProvider

Question

I am trying to move a project from VS 2008 to VS 2010. The project update wizard completed well, but the project does not compile. It says:

C: \ Windows \ Microsoft.NET \ Framework \ v4.0.30319 \ Config \ web.config (129): Error ASPCONFIG: Could not load type 'System.Data.Entity.Design.AspNet.EntityDesignerBuildProvider'.

I decided to stay with .net 3.5, but because of this error it seems that it is referencing version 4 of the framework. If I right-click on the solution and select "Properties," .NET 3.5 will be installed on the "Application" tab of the "Target" platform

I have VS 2008 installed on the same computer, and the project compiles and works fine.

Where am I going wrong?

Answer 1

Make sure you have this in your web.config.

<configuration> ... <system.web> <compilation debug="true" targetFramework="4.0"> <assemblies> <add assembly="System.Security, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" /> <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /> <add assembly="System.Data.Entity.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /> </assemblies> <buildProviders> <add extension=".edmx" type="System.Data.Entity.Design.AspNet.EntityDesignerBuildProvider" /> </buildProviders> </compilation> </system.web> </configuration>