www.makemkv.com

Hallo,
Erst vor kurzem kam Die Drei Musketiere / Die Vier Musketiere in 4K von Studiocanal 4006680 103334
Heraus. Leider ist es nicht möglich diese Ultra HD zu kopieren. Findet kein Index.

Mfg

Google Translate:

Just recently The Three Musketeers / The Four Musketeers came out in 4K from Studiocanal 4006680 103334
Out of here. Unfortunately it is not possible to copy this Ultra HD. Cannot find index.

If I understand correctly, i think you need to email the dump file to svq@makemkv.com.

From the UHD FAQ:

MakeMKV says that "the volume key is unknown for this disc"?
MakeMKV produces an AACS .tgz dump file whenever you try to open a disc for which the key is unknown, and will report that the dump has been created. Email the dump file to svq@makemkv.com.