id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host 10851,VM config file lost after host power off,Technologov,,"VBox: 4.1.16 (and 4.1.20) Host: Windows 7 x64 (and other Windows) When shutting down host, (after Windows update, or sudden power off) in some cases VBox does delete the *.vbox meta-data file, and the VM becomes ""inaccessible"" state. In some cases the file becomes corrupted and zero-bytes, and there are no *.vbox-tmp and no *.vbox-prev files to recover from. Workaround: copy [VM].vbox-tmp or [VM].vbox-prev as [VM].vbox can restore the VM in most cases. (something new users can't do) Recommended real fix: VBoxSVC must write down a history of transactions into the VM folder, per VM, [VM].vbox-transactions file, which should list all changes to the *.vbox file meta-data in a patch/diff format, and then, when VM becomes ""inaccessible"", VBoxSVC must attempt to recover the file until last transaction automatically, plus will allow manual recover and debug. NOTE: This bug is an old one, and AFAIK happens once every several weeks since v4.0.0 (but rarely) - still losing VM is *really* bad. Log attached. -Technologov, 2012-08-22.",defect,new,other,VirtualBox 4.1.20,,,,other,Windows