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

Question

I have a MVC4 web application that works fine on Visual Studio 2012, using the local IIS Express Server. When I publish the application to an IIS 8 web server running on Windows 2012, the initial login page displays correctly. However, using remote debugging, I see that when I check the credentials using the following line:

if (ModelState.IsValid && WebSecurity.Login(model.UserName, model.Password, persistCookie: model.RememberMe))

I get the error shown in the figure below:
_{(source: usf.edu)}

Answer 1

maybe something wrong with your Web.config file. Open the file and find the <runtime></runtime> tag. modify the version of MVC. For example, MVC 3

<runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
        <dependentAssembly>
            <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" />
        </dependentAssembly>
    </assemblyBinding>
</runtime>

Answer 2

Make sure it's looking for the correct version of the file. Mine were incorrect, the web.config file was pointing to later versions than what I had in the project.

In the properties I noted the version was 2.0.0.0 so I made it this version in the web.config file

Answer 3

The System.Web.Helpers.dll is included in the official Nuget package Microsoft.AspNet.WebPages.

Install that and the references should be corrected, and the file should be copied to your bin folder.

Answer 4

I was able to resolve this by downloading the Microsoft Web Platform Installer, searching for MVC and installing the "ASP.NET MVC3 (Visual Studio 2010 ) Released 4/11/2011" package. Close any Visual Studio instance prior to installing.

Answer 5

I had the same problem working with WCF service in IIS 8. Take a look at this solution Deploying ASP.NET, it worked for me.

Answer 6

After adding the correct version of MVC, the reference to Microsoft Web Helper is added but not of System.Web.Helper. Add this manually to your references.