Hi,

I am a small hosting provider, and a customer of mine has migrated Umbraco to us. However, when accessing https://customerdomain.com/Umbraco the following error appears:

Could not load types from assembly Umbraco.Forms.Core, Version=4.1.5.0, Culture=neutral, PublicKeyToken=null, errors: Exception: System.IO.FileLoadException: Could not load file or assembly 'System.Web.Mvc, Version=4.0.0.0, 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) File name: 'System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

=== Pre-bind state information === LOG: DisplayName = System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 (Fully-specified) LOG: Appbase = file:///C:/Inetpub/vhosts/customerdomain.com/httpdocs/Umbraco/ LOG: Initial PrivatePath = C:\Inetpub\vhosts\customerdomain.com\httpdocs\Umbraco\bin

Calling assembly : Umbraco.Forms.Web, Version=4.1.5.0, Culture=neutral, PublicKeyToken=null.

LOG: This bind starts in default load context. LOG: No application configuration file found. LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet.config LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config. LOG: Post-policy reference: System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/umbraco/8bacb902/2bcaafbd/System.Web.Mvc.DLL. LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/Temporary ASP.NET Files/umbraco/8bacb902/2bcaafbd/System.Web.Mvc/System.Web.Mvc.DLL. LOG: Attempting download of new URL file:///C:/Inetpub/vhosts/customerdomain.com/httpdocs/Umbraco/bin/System.Web.Mvc.DLL. WRN: Comparing the assembly name resulted in the mismatch: Major Version ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated

The server is running Microsoft .NET Framework Version:4.0.30319 and ASP.NET Version:4.7.2623.0.

The version of System.Web.Mvc in the /umbraco/bin folder is 5.2.3, so I have added this to the web.config:

        <dependentAssembly>
            <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" culture="neutral" />
            <bindingRedirect oldVersion="0.0.0.0-5.2.3.0" newVersion="5.2.3.0" />
        </dependentAssembly>

But still not working.

Would you know why I get this error and how to solve/troubleshoot it? Thank you.