Re: "Cannot open the disk 'XXX' or one of the snapshot disks it depends on. reason: failed to lock the file.

I know it's a few years since this was posted but deleting the LCK folders worked for me a few minutes ago on my Ubuntu 12.04 LTS machine.

Absolute life saver - almost thought I was going to have to rebuild the machine and waste most of a weekend's work.

Off to back up.

Thanks.