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Will upgrade of .net framework from 3 to 4 will shut down all the applications running in .net 3.0.? I had the server in which we have hosted some applications in IIS. But what i have seen is due to upgrade of framework all applications were stopped. Was that correct?

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migrated from Oct 25 '11 at 2:28

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They use different versions of the CLR, so I don't see any reason why existing applications would be stopped. Have you tried it? Do you mean they were stopped by the system, or as part of your own procedures? – Cocowalla Oct 24 '11 at 13:06
Not only IIS hosted apps , but also some windows applications were stopped while upgradation. I dont know the exact reason. We are still investigating and i can see from eventlog that system is rebooted after upgrade. Thats why previously running applications were stopped. – Ershad Oct 24 '11 at 13:11

You can run .NET 3.0 and 4.0 applications side-by-side.

However, as you bring .NET 4.0 applications online, you will need to configure the website to use 4.0 and also set any apps running 4.0 to run in a different Application Pool. (This may be why the old ones were stopped.)

There are instructions here and here for doing that if you need them.

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But when some applications are already running in 3.0 and simultaneously 4.0 upgrade happens. Thne what will happen? – Ershad Oct 24 '11 at 13:32
It depends on if someone visits a page in a .NET 2.0 - 3.5 website and a .NET4.0 website while they are running in the same application pool. If that happens, all applications will crash and you'll get event log entries explaining why. – David Oct 24 '11 at 13:40

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