[entity-framework] Could not load file or assembly 'EntityFramework' after downgrading EF 5.0.0.0 --> 4.3.1.0

After too hastily upgrading to EF 5.0.0.0 RC and being stuck with a .NET 4.5 project that wouldn't deploy to Windows Azure (.NET 4.0 and below), I decided to downgrade to EF 4.3.1.0.

I'm unsure of the best way to perform this type of migration but my strategy is to use "Manage NuGet Packages" identify which projects reference the package, uncheck the package from each project, install the replacement and recheck the correct projects.

Unfortunately, after doing this, my solution produced the titular "FileLoadException".

Could not load file or assembly 'EntityFramework, Version=5.0.0.0, Culture=neutral,        
PublicKeyToken=b77a5c561934e089' or one of its dependencies. The located assembly's 
manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

I searched through the solution files particularly packages.config for references to EF 5.0.0.0 RC but could find none.

I got same issue. I was getting the System.Data.Entity.Infrastructure; error which is only part of v5.0 or later. Just right click the Reference and select "Manage NuGet Package" . In the Installed Package option , uninstall the Entity FrameWork which is already installed and Install the 5.0 version. It solve the problem. I was trying manually get the System.Data.Entity reference , which was not success.

I received the exact same error message. Except that my error message said "Could not load file or assembly 'EntityFramework, Version=6.0.0.0...", because I installed EF 6.1.1. Here's what I did to resolve the problem.

1) I started NuGet Manager Console by clicking on Tools > NuGet Package Manager > Package Manager Console 2) I uninstalled the installed EntityFramework 6.1.1 by typing the following command:

Uninstall-package EntityFramework

3) Once I received confirmation that the package has been uninstalled successfully, I installed the 5.0.0 version by typing the following command:

Install-Package EntityFramework -version 5.0.0

The problem is resolved.

I have this issue, and all I did was make sure that I was referencing the right .Net framework in all the projects then just change the web.config from

From

<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>

To

<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework" requirePermission="false"/>

All works..

While Building a Project, if in the project properties it shows that it is build under Target.NET Framework 4.5, update it to 4.6 or 4.6.1. Then the build will be able to locate Entity Framework 6.0 in the Web.config file. This approach solved my problem. Selecting Target framework from Project Properties

I had the same issue when updating an older project. Here's what I did to resolve it:

• Converted all projects to .NET 4.5.
• Uninstalled the NuGet package for Entity Framework 5.
• Reinstalled the NuGet package for Entity Framework 5.
• Cleaned the solution.
• Rebuilt the solution.

The projects that used Entity Framework 5 and .NET 4 were installing the Entity Framework dll version 4.4. Once I switched the .NET version to 4.5 on the project, the dll version would be 5.

My problem came from older projects being on .NET 4 and a newer project running .NET 4.5 so there were 2 dll versions of EF in my solution.

Hope this helps someone...

In your references click on the EntitiyFramework . Go to properties and set the specific version to False. It worked for me.

I had a similar issue running unit tests using MSTEST under Jenkins. The fix in my case was to remove "Version=6.0.0.0, " as shown below:

Old:
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=xxxx" requirePermission="false" />

New:
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Culture=neutral, PublicKeyToken=xxxx" requirePermission="false" />

I had to make this change is several App.config and Web.config files in my multi-project solution.

public Configuration()
{
    AutomaticMigrationsEnabled = false;

    // register mysql code generator

    SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());
}

I find out that connector 6.6.4 will not work with Entity Framework 5 but with Entity Framework 4.3. So to downgrade issue the following commands in the package manager console:

Uninstall-Package EntityFramework

Install-Package EntityFramework -Version 4.3.1

Finally I do Update-Database -Verbose again and voila! The schema and tables are created. Wait for the next version of connector to use it with Entity Framework 5.

I had a similar issue:

1. On my ASP.NET MVC project, I've added a Sql Server Compact database (sdf) to my App_Data folder. VS added a reference to EntityFramework.dll, version 4.* . The web.config file was updated appropriately with the 4.* configuration.

   <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>

2. I've added a new project to my solution (a Data Access Layer project). Here I've added an EDMX file. VS added a reference to EntityFramework.dll, version 5.0. The App.config file was updated appropriately with the 5.0 configuration

   <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />

On execution, when reading from the database the app always thrown the exception Could not load file or assembly 'EntityFramework, Version=5.0.0.0 ....

The issue was fixed by removing the EntityFramework.dll v4.0 from my MVC project. I've also updated the web.config file with the correct 5.0 version. Then everything worked as expected.

If you used the Visual Studio 2012 ASP.NET Web Forms Application template then you would have gotten that reference. I'm assuming it's the one you would get via Nuget instead of the framework System.Data.Entity reference.

I had similar issue with selenium: I downgraded my selenium using NuGet and got the same error message. My solution was to remove the newer version lines from the app.config file.