www.makemkv.com

Starting with version 1.10.6 you may get a debug dump message "Please send the file dump_SD_xxxx.tgz ..." when opening certain blu-ray discs, not necessary protected with BD+.
If you encounter a message like this then please do send the produced dump file, even if the disc opened without issues.
Thank you.

Does the message say where to send it to?

I came here to ask the same question. I was ripping one of my older Blu-Ray's and I got the same message. It appears to have ripped fine. I sent the file to support@makemkv.com like it said.