<add assembly="System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

It shows that the assembly you referenced in the project has different version(4.0.0.1) as what you have in web.config(4.0.0.0).

Please check that the referenced assembly for System.Web.Mvc is the same as written in the web.config.

If not then add reference to the appropriate assembly. Right click References -> Add Reference -> ...

Install Nuget Package Microsoft.AspNet.Mvc for all the project referencing System.Web.Mvc dll

Example: Install-Package Microsoft.AspNet.Mvc