You may get following HTTP error if you don’t have ASP feature installed in IIS 7/7.5/8/8.5 server.
HTTP Error 404.3-Not Found
The page you are requesting cannot be served because of the extension configuration. If the page is script, add a handler. If the file should be downloaded, add a MIME map.
- It’s possible a handler mapping is absent. By default, the static file handler functions all content.
- The feature you want to use might not be installed.
- The correct MIME map is not allowed for the application or website. (Cautionary: Do not make a MIME map for content that users shouldn’t download like .config files or .aspx pages)
- If ASP.NET doesn’t installed.
How to fix HTTP Error 404.3 – Not Found
You need to install IIS sub components from
Control Panel -> Programs and Features -> Turn Windows features on or off
Internet Information Services -> World Wide Web Services -> Application Development Features
After that, you should check ASP.NET option. After clicking on ASP.NET option ISAPI Filters, ISAPI Extensions, .NET Extensibility options will be selected automatically. Make sure that specific version is checked. These options are divided into 4 and 4.6 in Windows server.
Run the following command from cmd:
For 32bit (x86) Windows:
For 64bit (x64) Windows
Lastly, check in IIS manager, that your application uses application pool with .NET framework version 4.0.