Could not load file or assembly 'System.Web.We

问题:

I just upgraded packages in an MVC 3 project (ASP.net 4), and now I am getting the following error message when accessing a page in that project:

Server Error in '/MyApplication' Application.

Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' 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 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Assembly Load Trace: The following information can be helpful to determine why the assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' could not be loaded.

=== Pre-bind state information === LOG: User = IIS APPPOOL\ASP.NET v4.0 LOG: DisplayName = System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 (Fully-specified) LOG: Appbase = file:///C:/.../ LOG: Initial PrivatePath = C:...\bin Calling assembly : Microsoft.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. === LOG: This bind starts in default load context. LOG: Using application configuration file: C:...\web.config LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config. LOG: Post-policy reference: System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/.../cb62a7b2/327a0353/System.Web.WebPages.Razor.DLL. LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/.../cb62a7b2/327a0353/System.Web.WebPages.Razor/System.Web.WebPages.Razor.DLL. LOG: Attempting download of new URL file:///C:/LeGroupeHtmSVN/.../UpDir.Web/bin/System.Web.WebPages.Razor.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 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]
Microsoft.Web.Helpers.PreApplicationStartCode.Start() +0

[InvalidOperationException: The pre-application start initialization method Start on type Microsoft.Web.Helpers.PreApplicationStartCode threw an exception with the following error message: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040).]
System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) [phone]
System.Web.Compilation.BuildManager.CallPreStartInitMethods() +465
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +1167

[HttpException (0x80004005): The pre-application start initialization method Start on type Microsoft.Web.Helpers.PreApplicationStartCode threw an exception with the following error message: Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040).]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) [phone] System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4869125

-------------------------------------------------------------------------------- Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

In my web.config file, and in my application, I am referencing System.Web.WebPages.Razor v1.0.0.0:

  <dependentAssembly>
    <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-1.0.0.0" newVersion="1.0.0.0" />
  </dependentAssembly>

I don't even know whether I could be using System.Web.WebPages.Razor v2.0.0.0 with .Net 4.

Now, how do I find out what is referencing System.Web.WebPages.Razor v2.0.0.0?

回答1:

how do I find out what is referencing System.Web.WebPages.Razor v2.0.0.0?

Just read your exception stacktrace:

Calling assembly : Microsoft.Web.Helpers, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35

So it seems that you are using the Microsoft.Web.Helpers which in turn depends on System.Web.WebPages.Razor, Version=2.0.0.0.

回答2:

So simple. In Nuget Package Manager Console:

Update-Package Microsoft.AspNet.Mvc -Reinstall

回答3:

This problem started when I did 'Remove Unused References'. The website still worked on my local machine, but did not worked on the server after publishing.

I fixed this problem by doing the following,

1. Open 'Package Manager Console' in Visual Studio
2. Uninstall-Package Microsoft.AspNet.Mvc
3. Install-Package Microsoft.AspNet.Mvc

回答4:

In ASP.NET MVC 4, the namespace is not System.Web.WebPages.Razor, but System.Web.Razor

That worked for me, change your web.config.

回答5:

After much pain, googling and hair pulling, I ended up uninstalling MVC 4 using nuget, deleting all references to MVC, razor and infrastructure from the web config, deleting the dlls from the bin folder - then using nuget to reinstall everything. It took less time then trying to figure out why the dlls did not match.

回答6:

I was getting the same error after adding an unnecessary reference to System.Web.Mvc. I removed all the references I could find, but nothing seemed to work. I finally deleted the project's bin folder and the error went away after a rebuild.

回答7:

I uninstalled ASP.NET MVC 4 using the Windows Control Panel, then reinstalled it by running AspNetMVC4Setup.exe (which I got from https://www.microsoft.com/en-us/download/details.aspx?id=30683), and that fixed the issue for me.

In other words, I didn't need to use Nuget or Visual Studio.

回答8:

I also received this error and tried everything I could find online and it wouldn't go away. In the end, I just downgraded MVC from 5.2.3 to 4.0.40804. I don't like this solution because eventually I'll need to use MVC 5, but it works for now. Hope this helps others.

回答9:

Short:
In you have this problem with a pure Web API project (and thus don't need razor), try to add it anyway, rebuild, then remove it.

Long story:
I had this problem with a brand-new pure Web API project, except that the stacktrace pointed "System.Web.Mvc" as Calling assembly (see Darin's answer). No reference to MVC, Razor or anything like that in my project though...
I decided to add the MVC packages (AspNet.Mvc, AspNet.WebPages and AspNet.Razor) to check if there was any subsequent problem.
The WebApi app then launched perfectly fine. Then I removed the exact same packages and everything was still OK.

Hope it helps someone.

回答10:

In some cases, just install web page 2 to resolve this (resolved with my case - deploy to local web page using web api )

https://www.microsoft.com/en-us/download/details.aspx?id=34600

回答11:

If earlier working project crashing suddenly with mentioned error you can try following solution.

• Delete the bin folder of respective web/service project.
• Build

This worked for me.