Could not load file or assembly ‘System.Web.WebPages.Razor, Version=3.0.0.0

I want using external logins so I installed Oauth by package manager:

 PM> Install-Package Microsoft.AspNet.WebPages.OAuth

Then I got this error after installed it then I install razor:

PM> Install-Package Microsoft.AspNet.Razor

But I still have this exception. Further more my application is an asp.net application and not a MVC application. Thanks for help.

[FileNotFoundException: Could not load file or assembly 'System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.]
   Microsoft.Web.WebPages.OAuth.PreApplicationStartCode.Start() +0

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Apologies in advance for this lo-tech suggestion, but another option, which finally worked for me after battling NuGet for several hours, is to re-create a new empty project, Web API in my case, and just copy the guts of your old, now-broken project into the new one. Took me about 15 minutes.

Method 2

You have upgraded to Razor 3. Remember that VS 12 (until update 4) doesn’t support it. Install The Razor 3 from nuget or downgrade it through these step

geekswithblogs.net/anirugu/archive/2013/11/04/how-to-downgrade-razor-3-and-fix-the-issue-that.aspx

Method 3

Another option is to update the Microsoft.AspnNet.Mvc NuGet package. Be careful, because NuGet update does not update the Web.Config. You should update all previous version numbers to updated number. For example if you update from asp.net MVC 4.0.0.0 to 5.0.0.0, then this should be replaced in the Web.Config:

    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    </sectionGroup>
  </configSections>

 <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

<pages
    validateRequest="false"
    pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
  <controls>
    <add assembly="System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />
  </controls>
</pages>

Method 4

Update using NuGet Package Manager Console in your Visual Studio

Update-Package -reinstall Microsoft.AspNet.Mvc

Method 5

What worked for me is: right click on project properties then Manage Nugget Packages
then chose update tab then chose Microsoft.AspNet.Razor then downgrade to version 3.0.0

Method 6

I went a little bit further. My project is pretty big and I refuse to create a new project and then move everything from the old to the new. Boring.

My solution
I forced NUGET to reinstall everything, I took the names from the project file under 'Import Project=...', removed the '.props' extension. Open the NUGET console on the V/Studio Tool Menu:

On my project (partial)

Update-Package -reinstall Microsoft.Net.Compilers.Toolset
Update-Package -reinstall Microsoft.Net.Compilers
Update-Package -reinstall Microsoft.CodeAnalysis.Analyzers
Update-Package -reinstall Microsoft.TypeScript.MSBuild
Update-Package -reinstall EntityFramework
Update-Package -reinstall Microsoft.TypeScript.Default
Update-Package -reinstall Microsoft.CodeDom.Providers.DotNetCompilerPlatform
Update-Package -reinstall Microsoft.Common
Update-Package -reinstall Microsoft.TypeScript.MSBuild

Finnaly
And then, on the same project file, I deleted all the lines containing <Error Condition="!Exists('packages.... to avoid compiler missing package failure .

My project and solutions are now up and running.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0