I'm converting my project from MVC 4 to MVC 5 (and .Net 4 to .Net 4.5.2, which is the real driver of the changes.)
When I run one of my pages I get this error (blank space added by me for easier reading)
[A]System.Web.WebPages.Razor.Configuration.HostSection cannot be cast to [B]System.Web.WebPages.Razor.Configuration.HostSection.
Type A originates from 'System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context 'Default' at location 'C:\windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.WebPages.Razor\v4.0_1.0.0.0__31bf3856ad364e35\System.Web.WebPages.Razor.dll'.
Type B originates from 'System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context 'Default' at location 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\studentportal3g\2204bad2\aece9b3b\assembly\dl3\ad80387c\91adbf51_fc73d101\System.Web.WebPages.Razor.dll'.
When I first saw this is though, Ah easy! Not so much :)
I've gone over every project and made sure it's version is upgraded to MVC 5 which has the 3.0.0.0 version of System.Web.WebPages.Razor.dll.
Clean rebuild, still get the error. No problem , I'll delete the cached temp files.
Clean rebuild, still get the problem. I go back, manually check each version of System.Web.WebPages.Razor.dll, in the references of each project that has a reference to it. I check my folder where I copy dlls to make references to them manually, it's not there.
If my solution doesn't' contain a copy of the DLL or a reference to the DLL, and I've manually deleted the cache folders in 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET
Files\studentportal3g...
Where is the old bad dll coming from? How do I fix this error? How do I prevent it happening again?
Thanks,
Eric-
Visual Studio is a great tool, but it doesn't always make the right choices when it comes to upgrading dependencies, nor does it support every possible option available in MSBuild. Whenever you find yourself in a bind such as this you should manually review and (if necessary) edit your .csproj
file in order to resolve it.
The problem isn't that your file exists in the GAC or that it has not been installed by NuGet, the issue is most likely that one of your project files still has a reference to the old version of System.Web.WebPages.Razor
version 1.0.0.0
, and you need to find all references to it and change them to 3.0.0.0
accordingly.
Unload Project
.Edit <projectName>.csproj
.System.Web.WebPages.Razor
and update the version and the HintPath
accordingly (as shown below). Make sure the HintPath
you use actually points to an existing file.<Reference Include="System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
<Private>True</Private>
<HintPath>..\packages\Microsoft.AspNet.WebPages.1.0.20105.408\lib\net40\System.Web.WebPages.Razor.dll</HintPath>
</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>
You should also go through the web.config
and /Views/web.config
files to ensure that they are not referencing any old versions of this assembly.
NOTE: If the above instructions don't solve your issue, the issue likely is outside of your solution. Most likely there is a 3rd party library that is referencing the old version of the file somewhere. If so, you could attempt to get an updated version of the DLL.
You may also want to check out this question.
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