virtualbox.org

FYI dudes n dudettes...

My upgrade from VB 4.1.6 to 4.1.8 caused "verr_ssm_data_unit_format_changed".
Host is running Win7 x64
Guest is running Win2K8 R2

The guest was in saved state before upgrading VB and the problem occurred when restoring the machine making it impossible to start...
I reverted back to 4.1.6 and the machine restored just fine. I then shut the machine down and upgraded again to 4.1.8 and the machine now booted ok.

Worth noting is I also had another saved guest running Win7 x64 and this one never failed restoring.

This happens sometimes when you do not shut the guest/s down before upgrading. You could have clicked the discard icon in the VMM instead of the remove,shutdown,install though. Still it has always been suggested to shut down the guests prior to upgrading.