404.3 - IIS - Not Found The page you are requesting cannot be served because of the extension configuration

Normally this error comes when you try to run any application on IIS for the first time. This error could be with any of the following type of requests:

1. Asp.net website - It means you are trying to run normal asp.net website.
2. Web Service - When you try to host web service on IIS.
3. WCS Service - When you try to host WCF Service on IIS.

To resolve this error:

1. Click the Start button, and then click Control Panel.
2. Click Programs, and then click Programs and Features.
3. On the Tasks menu, click Turn Windows features on or off.
4. In Role, select and IIS.
5. In features, select .net framework 4.5 features > WCF Services > HTTP Activation.
6. Save the setting.