"The page you are requesting cannot be served because of the extension configuration." error message
asp.net, iis
Solution
Use aspnet_regiis.exe to register version of .NET framework you are using.
This is a common issue and happens when IIS is installed after VS or .NET framework.
Note - for Windows 8/10 users, see the other answer by JohnOpincar below. And also the comment/tip from Kevin Brydon.
Problem
I'm getting this error message when trying to run my application. I don't know how to fix it: HTTP Error 404.3 - Not Found The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map. Here's a screenshot of the error page: What can I do to fix this error?