Unable to run website with ASP.Net version 1.1; while 4.0 works

Question

ASP.Net application (Version 1.1) that was working fine in live environment.

I encountered a problem all of a sudden that some of the functionalities stopped working. I tried simulating the problem in test environment. I found it is with ASP.Net version under IIS -> Websites -> Mywebsite -> properties -> asp.net tab -> asp.net version. Changing that version from 4.0.xxxx to 1.1.xxxx worked.

But when i did the same in live, it isn't.
I tried browsing the page and i get the message saying "page cant be found".
I ran "C:\Windows\Microsoft.Net\Framework\v1.1.xxxx\aspnet_regiis -u" first C:\Windows\Microsoft.Net\Framework\v1.1.xxxx\aspnet_regiis -i after that.

Once this registration is over, I checked the asp.net version in the iis for Mywebsite, it got changed back to 4.0.xxxxx I really dont know why it's happening. I could access the pages with 4.0.xxxxx but i will need them to be accessed with 1.1.xxxx

Can someone throw some light please?

Environment: Windows Server 2003

Answer 1

I got the answer!

It was happening due to some microsoft patch updates. That turned web service extensions for asp.net 1.1 to be blocked.

I followed the below steps to get it working!

1. Go to IIS (The version i use is 6.0)
2. Expand Machine Name
3. Click Web Service Extensions

At the right side i could see the available .Net frameworks. Right click ASP.Net v1.1.4322 > Allow. That's it. Problem solved.