Why Does My MVC 4 to MVC 5 Upgrade Fail with a 'System.Web.WebPages.Razor.Configuration.HostSection Cannot Be Cast' Error?

Troubleshooting "System.Web.WebPages.Razor.Configuration.HostSection cannot be cast" Error During MVC 4 to MVC 5 Upgrade

During the transition from ASP.NET MVC 4 to 5, a user encountered the following error:

[A]System.Web.WebPages.Razor.Configuration.HostSection cannot be cast to [B]System.Web.WebPages.Razor.Configuration.HostSection.

Investigating the references in each project, deleting temp files, and verifying the installation of the updated System.Web.WebPages.Razor.dll seemed to hold no solution.

The Root of the Problem

The issue lies in a project file still referencing the older version of System.Web.WebPages.Razor (1.0.0.0) instead of the updated version (3.0.0.0). To resolve this:

Step-by-Step Resolution

1. Unload and Edit .csproj: Right-click on the project and select "Unload Project" and "Edit .csproj."
2. Search for References: Locate references to "System.Web.WebPages.Razor" and update the version and HintPath as necessary. Ensure the HintPath leads to an existing file.
3. Repeat for Dependent Projects: Perform these steps for all dependent projects and any DLLs outside the solution.

Updated Reference:

<reference include="System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
  <private>True</private>
  <hintpath>..\packages\Microsoft.AspNet.WebPages.3.0.0\lib\net45\System.Web.WebPages.Razor.dll</hintpath>
</reference>

Additional Considerations

• Check web.config and /Views/web.config files for references to old versions of the assembly.
• Consider getting an updated version of the DLL if the issue persists despite the above steps.
• Consult the similar question mentioned in the provided answer for further assistance.

The above is the detailed content of Why Does My MVC 4 to MVC 5 Upgrade Fail with a 'System.Web.WebPages.Razor.Configuration.HostSection Cannot Be Cast' Error?. For more information, please follow other related articles on the PHP Chinese website!