How to fix HTTP Error 404.3 - Not Found (aspx file not recognized by IIS)
To run ASP.Net pages on IIS, ASP.Net has to be registered with IIS so that it can handle requests for ASP.Net pages.
It is highly recommended to install IIS while you install Windows. So IIS is already installed and you can install new versions of .Net Framework without any problem.
So IIS is automatically configured to handle ASP.Net requests by the .Net Framework installation package.
But if IIS is not installed when you install a .Net Framework version then the registration process cannot happen and needs to be done later once IIS has been installed.
In such case you can get an error like below:
‘The page you are requesting cannot be served because of the Multipurpose Internet Mail Extensions (MIME) map policy that is configured on the Web server. The page you requested has a file name extension that is not recognized, and is not allowed.
Error Code: 0x80070032’
To fix it, there is a utility installed as part of a .Net Framework installation which allows you to register the version of .Net Framework with IIS once it has been installed.
The utility is called ‘aspnet_regiis.exe’. It is located under %WindowsDir%\Microsoft.NET\Framework\vx.y.zzzz\
1. Open a command prompt and navigate to the folder %WindowsDir%\Microsoft.NET\Framework\ vx.y.zzzz\ (use ‘cd’ command to change the current directory). E.g for .NET Framework version 4.0:
2. Then enter the following command:
The command prompt will show message ‘Start installing ASP.NET (version…)
Finished installing ASP.NET (version…)’
This will register ASP.Net with IIS.