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i really confused about this issue ...

i have some web apps that are using difference .net framework 3.5 + 4

i configured them in iss by setting their ver...

it seems my configuration in dns and iis are ok - but Server Application Unavailable error comes up many times...

how can i solve this problem ?

for solving that i found the below link :

but which ver of aspnet should i uninstall and reinstall?

is there another way for solve this issue?

thanks in advance

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up vote 1 down vote accepted

You cannot run multiple framework versions in the same app pool. The solution is to put the different parts of the site into different app pools, or to upgrade them all to the same version. Here's an old blog of mine about running multiple framework versions, but it's still applicable.

However, since you're using IIS7, it's odd that you would run into errors like that. The issue isn't really the same. Just the same, try breaking your site into multiple app pools, one for each framework version needed. That will prevent clashes.

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