The backup is on a USB hard drive. I have backed-up PSE11 twice and tried to restore into PSE13 with no luck. (It restores (seemingly) all the photos - just not the catalogue.)
I also installed a trial copy of PSE12 on another computer, and restored a PSE11 backup (from the USB hard drive) onto that. It worked OK except I had to re-connect all the files, and the Events and Places tags were not visible over in the right-hand window, but the People tags were (the Events and Places tags were attached to the actual photos - just no Events or Places tags in the tag browser).
I then backed-up the PSE12 database and tried to restore into PSE13. I can't remember the error I got that time (not the one above), but then I realised all the PSE12 photos needed re-connecting, so I did that and backed it up again, and again tried to restore a PSE12 into PSE13. I got the same error message above that I get when trying to restore a PSE11 database into PSE13.
I was thinking of upgrading to PSE13 myself, but am having doubts now.
Ian