www.makemkv.com

Thanks, it worked after I cleaned the Disc, it never looked dirty, but it helped. I guess it's like blowing into the cartridge.

Okay, I redownloaded MakeMKV and retried converting them. This time I could successfully convert Prinsoners, even though it's the same version of MakeMKV. John Carter still didn't work, I hope my Log helps. Debug log started at Thu Jul 2 13:10:15 2015 , written by MakeMKV v1.9.4 darwin(x86-release) ...

Up until now I could very reliably convert every Blu Ray into a MKV file. Yesterday I tried and failed multiply times at converting the PAL version of the movies "John Carter" and "Prisoners". I tried copying them with two different computers. I'm using OSX Yosemite and Mavericks...