How to solve a “HTTP Error 404.3 - Not Found” error?

Question

Simple problem. I start up VS2008 and create a new WCF Service application. This will create a default application with a few test methods showing it works. I press CTRL+F5 and

Answer 1

The problem, however, is then to re-register ASP.Net to IIS, which is explained below.

And also if you're on a 64bit machine always use Framework64 paths: C:\Windows\Microsoft.NET\Framework64\v4.0.30319>aspnet_regiis.exe -iru

Below is the explanation from Microsoft:

http://download.microsoft.com/download/0/A/E/0AEB3BC1-506E-4954-8AB1-4FA2EE75985C/ReleaseNotes.docx

When attempting to run a service that receives messages over the HTTP transport, you may receive an error similar to the following:

Server Error in '/WCFApplication' Application

Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

Description: An unhandled exception occurred during the execution of the current Web request. Review the stack trace for more information about the error and where it originated in the code. Exception Details: System.TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

This error can occur when IIS is installed after installing .NET Framework 4, or if the 3.0 version of the WCF Http Activation module is installed after installing IIS and .NET Framework 4.

To resolve this problem, you must use the ASP.NET IIS Registration Tool (Aspnet_regiis.exe,) to register the correct version of ASP.NET. This can be accomplished by using the –iru parameters when running aspnet_regiis.exe as follows:

aspnet_regiis.exe -iru

And credit, where it's due: Source