ASP.NET 1.1 & 2.0 on Windows XP breaks the VS.NET 2003 debugger

I rebuilt my system only last week due to it going to "blue-screen heaven" and hadn’t tried to debug anything in VS.NET 2003 until today.  Imagine my horror when I received a nasty message from VS saying the debugger failed to start on this server (localhost).  The only thing majorly different from my last build was that I have v2.0 of the .Net Framework installed.  Turns out the registration of ASP.NET 2.0 stopped the 1.1 debugger from starting because when I ran "aspnet_regiis -u" from the v2.0 framework folder to uninstall ASP.NET 2.0, the debugger started working again!
It seems a little strange that the two won’t work together so maybe there is a way to have them co-exist on the same dev. machine that I don’t know about.  If anyone reading this does know, please leave a comment!

One Comment on “ASP.NET 1.1 & 2.0 on Windows XP breaks the VS.NET 2003 debugger”

  1. Joseph says:

    It doesn’t seem strange at all to me. CLR 2.0 has new IL instructions that 1.1 did not have (IIRR). If your ASP.NET app is running under framework v2.0 then you have to use the framework v2.0 debugger. You can selectively set certain web apps to run under 1.0, 1.1 and 2.0 on the same machine using the command line options in aspnet_regiis.