The type 'Expression<>' is defined in an assembly that is not referenced

Question

In ASP.NET MVC 4.5.2 Framework.

after typing

@Html.LabelFor() or  @Html.EditorFor() 

in view

I'm getting Error: The type 'Expression<>' is defined in an assembly that is not referenced.You must add a reference to assembly 'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

I have added assembly reference System.Core.dll, Version 4.0.0.0, Runtime Version v4.0.30319. and also i did in web.config

Answer 1

I am not sure if you are still having this issue or not but i was having the same issue as well.

I was able to find the solutions here

https://stackoverflow.com/questions/6496223/compilation-error-in-net-4-0-web-config-linq-not-found

<add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>  <add assembly="System.Data.DataSetExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>  <add assembly="System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> 

I hope this helps..

Answer 2

This error means that Visual Studio is unable to locate the System.Web.Mvc assembly to power its intellisense for Razor views. One or both of the following may be required to fix it.

1. Ensure the version of the .NET framework for the compilation property in the main web.config (the one in the website root) is the same as that specified in the project properties.

[root]/Web.config:

<system.web>     <compilation targetFramework="4.6" /> 

Project Properties:

2. Ensure the version of the MVC assembly specified in the views web.config (the one in the views folder) is the same as the MVC assembly you are using in your project.

[views folder]/web.config:

<system.web.webPages.razor>     <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> 

MVC Assembly Reference Properties: