www.makemkv.com

The folder on your hard drive that has the blu-ray files has probably already been processed/decrypted by AnyDVD. Did you make the backup yourself or did you get it from somewhere else?

Thanks for your reply.
I got it from somewhere else and I see now that there is a subfolder "Any" in it ...

When I start MakeMKV to make a mkv from a Blu-Ray (in folder on my hdd), I get a warning that AnyDVD seems to be enabled and that errors may occur. However I don't have AnyDVD installed at all.
Although I get a playable mkv (without errors) I wonder what is wrong and why I get that warning.
Thanks ...