What happens if a .NET 1.1 and .NET 2.0 COM object are used in the same process?

Question

If a process loads both a .NET 1.1 COM object and a .NET 2.0 COM object, both using an in-process server, what happens? Does anything break with this configuration? Or would it be safer to make one of the objects an out-of-process server?

Answer 1

It depends which gets loaded first, because (prior to .NET 4) you can only have one version of the runtime loaded into a process. Either the .NET 1.1 object loads first, and the .NET 2.0 object falls over; or the .NET 2.0 object loads first and the .NET 1.1 object hopefully works.

You should probably consider upgrading the .NET 1.1 object to run on 2.0. If you don't, then either your application will fail, or the .NET 1.1 object will get loaded into 2.0 regardless.