I put .NET 2.0 on my client's web server the other day. Both 2.0 and 1.1 asp.net apps continued to run just fine.

Last night I was mucking with some of the mappings in .NET 2.0 and they weren't taking. So I did an iisreset. Here's where that led me (to the best of my recollection)

• 1.1 apps: Server Unavailable, 2.0 apps okay
• run aspnet_regiis -i  for 1.1
• 2.0 apps Server Unavailable, 1.1 apps okay
• iis reset
• 1.1 apps: Server unavailable, 2.0 apps okay
• aspnet_regiis -i for 1.1
• 1.1 apps okay, 2.0 apps okay
• close the MMC for iis
• 1.1 apps okay, 2.0 apps server unavailable
• aaargh!! That shouldn't have happened.
• aspnet_regiiis -i for 2.0
• 1.1 apps: Server Unavailable, 2.0 apps okay
• aspnet_regiiis -i for 1.1
• both okay
• don't touch a damned thing
• slept with my fingers crossed
• this morning - both still okay but I realize that clickonce deployment on the 2.0 site is broken.

Most of the above problems could have probably been avoided if I used some of the other available parameters for aspnet_regiis, such as -sn for fixing the mappings on just one application.

Update, though using the -sn was a good thing, the root of the problem (thanks to some reminders in the comments) was that I had neglected to create a separate Application Pool for the .net 2.0 websites. They were running in the same process as the asp.net 1.1 sites. So far, everyone has been behaving properly.

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