Could not load the assembly 'App_Web_xxxx'. Make sure that it is compiled before accessing the page.

Parser Error

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: Could not load the assembly 'App_Web_o3mx3ndd'. Make sure that it is compiled before accessing the page. Source Error:

Line 1:  <%@ master language="C#" autoeventwireup="true" inherits="MasterPage, App_Web_o3mx3ndd" %>
Line 2:  
Line 3:  <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>

Source File: /MasterPage.master    Line: 1

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.18447