c# - There is a duplicate 'entityFramework' section defined - EntityFramework6 upgrade

Question

I have recently updated EntityFramework in my WebAPI project from v5 to v6. Unfortunately it seems like somewhere, somehow, there is a reference that exists in some config somewhere that is set to v5.0. I can't seem to find it though; I will post my web.config below.

The error that shows up is:

There is a duplicate 'entityFramework' section defined.

I can't find that duplicate reference, but if I remove the single reference, then I get an error saying:

{"Message":"An error has occurred.","ExceptionMessage":"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)","ExceptionType":"System.IO.FileLoadException","StackTrace":" at System.Configuration.TypeUtil.GetTypeWithReflectionPermission(IInternalConfigHost host, String typeString, Boolean throwOnError) at System.Configuration.RuntimeConfigurationRecord.RuntimeConfigurationFactory.Init(RuntimeConfigurationRecord configRecord, FactoryRecord factoryRecord) at System.Configuration.RuntimeConfigurationRecord.RuntimeConfigurationFactory.InitWithRestrictedPermissions(RuntimeConfigurationRecord configRecord, FactoryRecord factoryRecord) at System.Configuration.RuntimeConfigurationRecord.CreateSectionFactory(FactoryRecord factoryRecord) at System.Configuration.BaseConfigurationRecord.FindAndEnsureFactoryRecord(String configKey, Boolean& isRootDeclaredHere)"}

Here is my web.config:

<?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=b77a5c561934e089" requirePermission="false" />
        <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
      </configSections>
      <connectionStrings></connectionStrings>
      <appSettings>
        <add key="webpages:Version" value="2.0.0.0" />
        <add key="webpages:Enabled" value="false" />
        <add key="PreserveLoginUrl" value="true" />
        <add key="ClientValidationEnabled" value="true" />
        <add key="UnobtrusiveJavaScriptEnabled" value="true" />
      </appSettings>
      <system.web>
        <compilation debug="true" targetFramework="4.5" />
        <httpRuntime targetFramework="4.5" />
        <authentication mode="None" />
        <pages>
          <namespaces>
            <add namespace="System.Web.Helpers" />
            <add namespace="System.Web.Mvc" />
            <add namespace="System.Web.Mvc.Ajax" />
            <add namespace="System.Web.Mvc.Html" />
            <add namespace="System.Web.Optimization" />
            <add namespace="System.Web.Routing" />
            <add namespace="System.Web.WebPages" />
          </namespaces>
        </pages>
        <profile defaultProvider="DefaultProfileProvider">
          <providers>
            <add name="DefaultProfileProvider" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" />
          </providers>
        </profile>
        <membership defaultProvider="DefaultMembershipProvider">
          <providers>
            <add name="DefaultMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/" />
          </providers>
        </membership>
        <roleManager defaultProvider="DefaultRoleProvider">
          <providers>
            <add name="DefaultRoleProvider" type="System.Web.Providers.DefaultRoleProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/" />
          </providers>
        </roleManager>
        <!--
                If you are deploying to a cloud environment that has multiple web server instances,
                you should change session state mode from "InProc" to "Custom". In addition,
                change the connection string named "DefaultConnection" to connect to an instance
                of SQL Server (including SQL Azure and SQL  Compact) instead of to SQL Server Express.
          -->
        <sessionState mode="InProc" customProvider="DefaultSessionProvider">
          <providers>
            <add name="DefaultSessionProvider" type="System.Web.Providers.DefaultSessionStateProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" />
          </providers>
        </sessionState>
      </system.web>
      <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <handlers>
          <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
          <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
          <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
          <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%Microsoft.NETFrameworkv4.0.30319aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
          <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%Microsoft.NETFramework64v4.0.30319aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
          <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
        </handlers>
      </system.webServer>
      <runtime>
        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
          <dependentAssembly>
            <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
          </dependentAssembly>
          <dependentAssembly>
            <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
          </dependentAssembly>
          <dependentAssembly>
            <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
          </dependentAssembly>
          <dependentAssembly>
            <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" culture="neutral" />
            <bindingRedirect oldVersion="0.0.0.0-1.3.0.0" newVersion="1.3.0.0" />
          </dependentAssembly>
        </assemblyBinding>
      </runtime>
      <entityFramework>
        <defaultConnectionFactory type="System.Data.Entity.Core.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
          <parameters>
            <parameter value="v11.0" />
          </parameters>
        </defaultConnectionFactory>
        <providers>
          <provider invariantName="System.Data.Entity.Core.SqlClient" type="System.Data.Entity.Core.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
        </providers>
      </entityFramework>
    </configuration>

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Answer 1

I was running into the exact same problem with having a Virtual Directory running EF6 and the root directory running EF5. Took me a few hours but I found a fix:

In the virtual directory Web.config, remove/comment out the configSection for EF6 (this stops you from duplicating the entityFramework section), add an assembly binding redirect (so it maps the root's EF5 configSection to EF6, but only in the Virtual Directory) and finally remove all the <entityFramework> configuration so it doesn't try to look for a configSection for EF6 in the Virtual Directory. My new Web.config file looks like this:

<configuration>
  <!--<configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
     --><!--For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468--><!-- 
  </configSections>-->

... rest of configuration ...

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="EntityFramework" publicKeyToken="b77a5c561934e089" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-5.0.0.0" newVersion="6.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <!--<entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=(localdb)v11.0; Integrated Security=True; MultipleActiveResultSets=True" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>-->

Next I added a DbConfiguration class to the assembly that contains the DbContext (this basically enables the EF6 code first configuration). For example:

public class MyConfiguration : DbConfiguration
{
    public MyConfiguration()
    {
        SetDefaultConnectionFactory(new SqlConnectionFactory("Data Source=(localdb)v11.0; Integrated Security=True; MultipleActiveResultSets=True"));
    }
}

And that was it, now I can have both EF versions working along each other. The tricky part for me was figuring out how to do the AssemblyBinding from EF5 to EF6 redirect. Also notice that I didn't change anything in the root Web.config.

Hopefully this helps someone out there having the same issue.