I've recently upgraded VS 2008 to VS 2010. On our server we have IIS6 installed and we can not change that in near future. Even though we will develop new applications to be deployed on IIS7 but if situation demands we may need to develop an application using .net 4.0 and to be deployed on IIS6, then in this case I wanted to know whether IIS6 supports .net 4.0 application or not?
If I can deploy, then do I need to take care of any configuration or any other setting I should change before deploying it?
My very complicate sites now are on iis6 running asp.net 4.0
My only issue moving from 3.5 to 4.0 was answered on this question: Default.aspx with IIS 6.0 and .Net 4?
and was also this point
<httpRuntime requestValidationMode="2.0" />
You can check all this list of breaking change moving to 4.0
http://www.asp.net/learn/whitepapers/aspnet4/breaking-changes
IIS6 does support ASP.NET 4.0, though if you want to use URL routing you'll need to make some tweaks.
This page has some details on this: http://blog.stevensanderson.com/2008/07/04/options-for-deploying-aspnet-mvc-to-iis-6/
Yes You can deploy .NET 4.0 with IIS 6 . refers to following links. for solutions..
Yes, you can deploy .net 4.0 app on IIS6 provided you should not use any .net 4.0 feature which is not supported by IIS6. We have deployed .net 4.0 app on IIS6 and it works fine.
来源：https://stackoverflow.com/questions/3132368/can-i-deploy-net-4-0-web-application-on-iis6