We are migrating from Windows 2003 running IIS6 to Windows 2008 running IIS7. Unfortunately, we have a lot of websites running on the .NET 1.1 framework. The following article has great step-by-step instructions for getting 1.1 running on IIS7:

http://blogs.iis.net/bills/archive/2008/06/02/installing-asp-net-1-1-with-iis7-on-vista-and-windows-2008.aspx

What has been extremely frustrating is the fact that I could not create an application pool and assign it (via the IIS7 manager) to run the 1.1 framework. There was no v1.1 option in the drop-down menu.

So, I spent a considerable amount of time searching for what I had missed during the install, or what was wrong with my configs, etc. I found nothing (maybe I’m not very good at searching). On a whim, I clicked the “?” help button on the “Add Application Pool” dialog, which turned up the following response:

Note: If you select .NET Framework version 1.1, the Managed pipeline mode list will be disabled. Additionally, if you are running IIS 7.0 on 64-bit Windows, and you have installed .NET Framework version 1.1, the value will not appear in the .NET Framework Version list when you add or edit an application pool. This is because .NET Framework version 1.1 installs under the Framework directory, but IIS reads values from the Framework64 directory on 64-bit Windows. You must set the managedRuntimeVersion attribute to v1.1 for the application pool in the configuration file directly or by using a tool such as IIS 7.0 command-line tool.

Now knowing that “IIS reads values from the Framework64″ directory on 64-bit Windows”, I recalled reading the following article by Won Yoo: http://blogs.iis.net/wonyoo/archive/2009/06/18/workaround-running-asp-net-1-1-on-vista-sp2-ws08-sp2.aspx. Won recommends that you copy the v1.1.4322/machine.config file from the “Framework” directory to the “Framework64” directory, and I had done this. But apparently, that is not what IIS7 is looking for to populate the drop-down.

An anonymous comment suggests creating a symlink instead:

MKLINK /d c:\Windows\Microsoft.NET\Framework64\v1.1.4322 
    c:\Windows\Microsoft.NET\Framework\v1.1.4322

And now, I have “.NET Framework v1.1.4322” as a choice in my dropdown! Thank you, anonymous!