www.makemkv.com

I have been having this error for a while now. Regardless of what disc I used. The logs would say Medium error, then invalid copyright and finally fail.

I was able to fix it on my system. Windows 8, v1.8.1

This is what I did
1) View -> Preferences
2) Select General Tab
3) Change "C:\Users\[Your Account Name]/.MakeMKV" to "C:\Users\[Your Account Name]\.MakeMKV" ... Note the direction of the final 'backslash'

Once I changed that and restarted MakeMKV everything worked.

I hope this helps others

Not to doubt you, but.... if changing a / to a \ "fixed" a medium error, Windows 8 is severely broken. In all versions of DOS and Windows since DOS 3.1, the "/" and "\" have been treated as identical in file names, INTERNALLY. COMMAND.COM and CMD.EXE are a different story, but the operating system itself would work either way. It's for compatibility with UNIX programs that might be ported to Windows.