Could not load file or assembly 'EntityFramework, Version=6.0.0.0

What am I doing wrong? How do I troubleshoot this?

I have a solution that has multiple projects. It is an MVC .NET 4.5 web application.

When invoking one of the projects AFTER I start in debug mode, I am getting this error.

The project that is causing this error has the following references:

They are both versions 6.0.0.0

Server Error in '/' Application. Could not load file or assembly 'EntityFramework, Version=6.0.0.0, 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) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IO.FileLoadException: Could not load file or assembly 'EntityFramework, Version=6.0.0.0, 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)

Source Error:


Line 139:        public vvvRepository() {
Line 140:            this._vvvEntities = new vvvEntities();
Line 141:        }
Line 142:
Line 143:        public vvvRepository(int commandTimeout) {


Source File: c:\tfs\PACE\eee Framework\branches\1.23\eeeService\Adapters\vvv\eeeService.vvv.DataAccess\vvvRepository.cs    Line: 141

Assembly Load Trace: The following information can be helpful to determine why the assembly 'EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' could not be loaded.


=== Pre-bind state information ===
LOG: User = eee\ksmith
LOG: DisplayName = EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
 (Fully-specified)
LOG: Appbase = file:///C:/tfs/PACE/eee Framework/branches/1.23/eeeService/vvvWebProd/zzz/zzz/
LOG: Initial PrivatePath = C:\tfs\PACE\eee Framework\branches\1.23\eeeService\vvvWebProd\zzz\zzz\bin
Calling assembly : eeeService.vvv.DataAccess, Version=1.22.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\tfs\PACE\eee Framework\branches\1.23\eeeService\vvvWebProd\zzz\zzz\web.config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
LOG: Attempting download of new URL file:///C:/Users/ksmith/AppData/Local/Temp/Temporary ASP.NET Files/root/1993f739/49fe9ab6/EntityFramework.DLL.
LOG: Attempting download of new URL file:///C:/Users/ksmith/AppData/Local/Temp/Temporary ASP.NET Files/root/1993f739/49fe9ab6/EntityFramework/EntityFramework.DLL.
LOG: Attempting download of new URL file:///C:/tfs/PACE/eee Framework/branches/1.23/eeeService/vvvWebProd/zzz/zzz/bin/EntityFramework.DLL.
WRN: Comparing the assembly name resulted in the mismatch: Major Version
ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.


Stack Trace:


[FileLoadException: Could not load file or assembly 'EntityFramework, Version=6.0.0.0, 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)]
   eeeService.vvv.DataAccess.vvvRepository..ctor() in c:\tfs\PACE\eee Framework\branches\1.23\eeeService\Adapters\vvv\eeeService.vvv.DataAccess\vvvRepository.cs:141
   ttt.ttt.get_Repository() in c:\tfs\PACE\eee Framework\branches\1.23\eeeService\vvvWebProd\zzz\ttt\ttt.cs:21
   ttt.ttt.GetDeviceBySerialNumber(String serialNumber) in c:\tfs\PACE\eee Framework\branches\1.23\eeeService\vvvWebProd\zzz\ttt\ttt.cs:52
   eee.EnterpriseServices.eeeFramework.zzz.Controllers.SettingsController.lookupDeviceForSettingsPost(String serialnumber) in c:\tfs\PACE\eee Framework\branches\1.23\eeeService\vvvWebProd\zzz\zzz\Controllers\SettingsController.cs:364
   lambda_method(Closure , ControllerBase , Object[] ) +180
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +59
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +435
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +60
   System.Web.Mvc.Async.AsyncControllerActionInvoker.InvokeSynchronousActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +50
   System.Web.Mvc.Async.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41() +75
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +44
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +139
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +73
   System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +126
   System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +323
   System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +44
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +139
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +74
   System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +68
   System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +184
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +136
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +66
   System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +40
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +68
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +65
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +45
   System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +151
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
   System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +66
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9628700
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18044 

Here is the app.config file of the project throwing the exception:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b761934e089" requirePermission="false" />
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.4.0.0, Culture=neutral, PublicKeyToken=b761934e089" requirePermission="false" />
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <!-- 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=6.0.0.0, Culture=neutral, PublicKeyToken=b761934e089" requirePermission="false" />
  </configSections>
  <connectionStrings>

  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="v11.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
  </entityFramework>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">

      <dependentAssembly>
        <assemblyIdentity name="EntityFramework" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="0.0.0.0-6.0.1.0" newVersion="6.0.0.0" />
      </dependentAssembly>

    </assemblyBinding>
  </runtime>
<system.serviceModel>
    <bindings>
      <wsHttpBinding>
      </wsHttpBinding>
    </bindings>

  </system.serviceModel></configuration>

What am I doing wrong? How do I troubleshoot this?

The Main project probably has a reference to a older version of Entity Framework and thus the older dll is in the build. Make sure that all projects that are using the problematic project have the new reference