What is the compatibility on .NET 4.0?

Question

We have several .NET applications developed in .NET 3.5 (Windows services, web applications, and WCF services) in different servers.

I'd like to migrate to .NET 4.0 and use VS.NET 2010.

• Does VS.NET 2010 compiles to .NET 3.5 to avoid full simultaneous migration, being able to stop using VS.NET 2008 but maintaining some applications in the previous version?

• Can I uninstall the .NET < 4.0 runtime and have only .NET 4.0 in my servers? Does it run applications compiled to previous framework versions?

Answer 1

1. Yes, it does
2. No you can't, the other runtime versions have to be installed. But you are able to run < 4.0 in a 4.0 .net process (e.g. a class library or so). msdn