I have vb6 com server (ActiveX DLL project) that is used by .NET code
Everytime I put changes into vb6 code and make dll, I have to recompile my .NET client code as well, because it looks like VB6 generates new GUIDs or versions to interfaces and com-objects.
I admit it's a good practice because changes are made but I'd like to disable this behavior to let my .NET client code be the same everytime I update my vb6 dll.
How can I tell VB6 to keep all GUIDs and versions for ActiveX dll the same no matter what changes are done to COM objects or COM interfaces?
The selection in the Project + Properties, Components tab matters. You have to select "Binary compatibility" here to force it to re-use old guids. And keep a copy of the DLL around to act as the "master" that provides the guids, check it into source control.
When you add new classes then you also have to update that copy so future versions will know to reuse the same guids for those added classes. Easy to forget, pretty hard to diagnose when you do.
It is very dangerous, reusing guids is a very strong DLL Hell inducer. You can get old client programs to continue using the new DLL as long as you careful avoid changing existing methods. Not just their method signature but also their implementation. An updated client that encounters an old version of the DLL will fail in a very nasty way, the access violation crash is near impossible to diagnose.