.net – System.Net.Http.Formatting.FormUrlEncodedMediaTypeFormatter Error

asp.netasp.net-mvcasp.net-mvc-4asp.net-mvc-5net

I am trying to upgrade my asp.net project from Mvc 4 to 5. I followed these instructions:

http://www.asp.net/mvc/tutorials/mvc-5/how-to-upgrade-an-aspnet-mvc-4-and-web-api-project-to-aspnet-mvc-5-and-web-api-2

When I want to compile my project I am getting following error :

Could not load type 'System.Net.Http.Formatting.FormUrlEncodedMediaTypeFormatter' from assembly 'System.Net.Http.Formatting, Version=5.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

If I add the reference to System.Net.Http.Formatting Version=4.0.0.0 then I am getting this error:

Assembly 'System.Web.Http, Version=5.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' uses 'System.Net.Http.Formatting, Version=5.2.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Net.Http.Formatting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

Can anyone help me?

Best Answer

I presume the unspoken part of your question (which @Adriano clearly did not infer) is that you don't see version 5.2.0.0 in the list when you go to add a reference, you see only version 4.0.0.0, right?

If so, the issue is probably your NuGet packages, which means you have an additional package you need to upgrade. In my case it was Microsoft.AspNet.WebApi.Client (apparently System.Net.Http.Formatting is in that assembly…?!?), which was upgraded in one of the projects in my solution but not the other. In your case, it looks like perhaps you need to install the upgrade of that particular package, and/or it was missed when you upgraded the other MVC packages.

Related Solutions

Asp.net-mvc – Could not load file or assembly ‘System.Web.Mvc’

I just wrote a blog post addressing this. You could install ASP.NET MVC on your server OR you can follow the steps here.

EDIT: (by jcolebrand) I went through this link, then had the same issue as Victor below, so I suggest you also add these:

* Microsoft.Web.Infrastructure
* System.Web.Razor
* System.Web.WebPages.Deployment
* System.Web.WebPages.Razor

.net – aspnet_compiler finding wrong version of System.Web.WebPages 1.0.0.0 instead of 2.0.0.0

I solved this problem by explicitly referencing the 2.0 assembly in Web.config. I suppose that for some reason, the ASP.NET compiler (in my case when running MvcBuildViews), uses the old 1.0 assembly first, if it is found.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <!-- … -->
  <system.web>
    <!-- … -->
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />
      </assemblies>
    </compilation>
    <!-- … -->
  </system.web>
  <!-- … -->
</configuration>

BTW: It looked like this problem occurred for the first time after I added a 3rd party ASP.NET MVC 3.0 component. That component works fine through the assembly binding, but it may be the reason why the ASP.NET compiler tries to load the 1.0 web pages first.

Best Answer

Related Solutions

Asp.net-mvc – Could not load file or assembly ‘System.Web.Mvc’

.net – aspnet_compiler finding wrong version of System.Web.WebPages 1.0.0.0 instead of 2.0.0.0

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