This disc uses a newer version of AACS (AACS17c &19)

[Furnace Inferno]

I’ve just tried to rip A Christmas Carol 3D and it came up with this error. Using 1.14.2, not really sure why when I’ve had disks up to v65 and it’s a much older film?

[Woodstock]

Most likely cause is there are errors when trying to read the section of the disk that contains the AACS information, and MakeMKV can't calculate a key.

Do you have debug logging turned on (see FAQ link in my signature)? What does the log show?

[Furnace Inferno]

I’ll check once I’m back tonight but it was both the 3D and 2D disk.

Edit:

Ok tried it again after backing up Aladdin and it’s working fine now on the 3D disk, I did also click on the link it provided to send debugs and emailed both but whatever it was, all good now.