Entity Framework version error in my small code first project

Question

I'm writing a small test project in order to get my feet wet with EF code first. Unfortunately, when I try compiling, I get the following error:

Assembly 'Backend, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' uses   
'EntityFramework, Version=4.3.1.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'  
which has a higher version than referenced assembly 'EntityFramework, Version=4.1.0.0,  
Culture=neutral, PublicKeyToken=b77a5c561934e089'   c:\Users\Kevin\Documents\Visual   
Studio 2010\Projects\CFTest\Backend\bin\Debug\Backend.dll   CFTest

For some reason, there's a versioning conflict, but I dunno how to fix it.

EDIT: My App.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.3.1.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
  </configSections>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=.\SQLEXPRESS; Integrated Security=True; MultipleActiveResultSets=True" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
</configuration>

Major Productions · Accepted Answer · 2012-07-12 00:58:25Z

2

My backend project had one version of EF while my MVC project came with another by default. Solved.

answered Jul 12, 2012 at 0:58

Major Productions

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3 Comments

Chris Knight Over a year ago

thanks for adding the solution. Now that I think of it, I have had the same issue with the same resolution before. Thanks.

Adam Tuliper Over a year ago

its pretty clear in the error message - backend has 4.3 and the web project during compile shows 4.3.1. You can remove both and simply do a install-package entityframework on both (or use -pre to get EF 5 RC code)

Major Productions Over a year ago

Yeah, but I didn't realize that my MVC 3 project came pre-loaded with a reference to EF 4.1 (I used the default project, not an empty one). Backend is a separate C# class library project that I explicitly installed a reference to 4.3.1 in. So, it was a conflict between my explicit EF reference and the one VS installs by default, which spanned two projects. But, whatever. It's fixed now and it's a lesson learned.

Chris Knight · Accepted Answer · 2012-07-12 00:42:28Z

0

It is conflict with the version of the .NET framework your project is using, and the version of the .NET Framework that the EF dll was compiled in. If you go to the add reference window for the project, the listing should say what .NET Framework version each DLL uses. Change you project target to use that version as well.

answered Jul 12, 2012 at 0:42

Chris Knight

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2 Comments

Major Productions Over a year ago

My project targets .NET 4, just like the DLLs

Chris Knight Over a year ago

Maybe one is using the Client Profile version? That could cause a conflict. Are you 100% sure the dll uses 4.0

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