Your recent crash was in fact caused by a different bug, LP #89009, which will have a fix committed shortly. Since you are getting passed the initial mounting of the partitions, I'm going to assume that the fix for this bug worked, and am therefore closing it.
** Changed in: migration-assistant (Ubuntu) Status: Needs Info => Fix Released -- Crashes when started up https://launchpad.net/bugs/85330 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs