Expression of type 'System.Web.Mvc.MvcWebRazor

问题:

I am getting this error when I try to run a project that I took over.

I assume I have a problem in my web.config, but I don't know what to look for.

Expression of type 'System.Web.Mvc.MvcWebRazorHostFactory' cannot be used for return type 'System.Web.WebPages.Razor.WebRazorHostFactory'

Any suggestions on the same are highly appreciated.

回答1:

Try to replace line in Web.Config

<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

to

<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

(set MvcWebRazorHostFactory to version 4.0.0.0)

回答2:

Set MvcWebRazorHostFactory to version 5.0.0.0 in ALL Views/web.config Under

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

回答3:

For everybody else still suffering, my solution was just like the one above, but with a tweak - I needed to match factory type version with version of System.Web.Mvc dll in your project references. To find out which version you have:

1. Expand "References" in your project

2. Right-click on System.Web.Mvc and look at version

   

3. Update web.config in your Views folder

So in my case it was as below:

  <system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

回答4:

I got the same error. What worked for me: Right-click on your project and select Manage NuGet Packages. Install Microsoft ASP.NET Razor. Rebuild the project.