www.makemkv.com

Found the solution: I didn't have drive letters for my drives before but used the function "Mount in the following empty NTFS folder" for each drive. I had done this to avoid a long and useless list of empty drives in my file explorer. Now that I have assigned drive letters, all 11 of the drives are ...

I have to reply here because I have a similar problem. My system has 11 drives and Windows recognizes all of them. Makemkv recognizes only 10 - one drive less. Is there a reason for this? 🤔

Howto:
Turn back your system time for one month so you're back in April
Make sure you've got the newest version of MakeMKV and start it
Go to Help > Register and paste the April beta key (regardless if you've done this before)
Close MakeMKV and restart it
Start ripping - should work fine ...

In the meantime, I notice that the public KEYDB.cfg (downloadable from here) already contains these two entries:
0x4DBCC54736D7F3FE4A163CB63B24308330238135 = THE_ABYSS (THE ABYSS - Ultra HD™) | D | 2024-01-25
0xF4F1CA045FF572B8D11E44AC49566A76A68F794F = THE_ABYSS (THE ABYSS - Ultra HD™) | D | 2024 ...

Just received the German 4K Disc of THE ABYSS. This is what MakeMKV (Windows) says:
[...]
Saved AACS dump file as C:\Users\.../.MakeMKV/MKB20_v77_THE_ABYSS_34FA.tgz
The volume key is unknown for this disc - video can't be decrypted
Failed to open disc

What now?