For the specific case of upgrading the kernel packages on a live system, I have found a trick that seems to work for me. I can't be sure it won't break something, though.
The problem in this case cannot be solved by manually running the grub utilities, as the package manager will always attempt to run grub-update by itself. This runs grub-probe on /, which is the aufs and cannot apparently be probed. If grub-probe is instead run on the /cdrom path, which contains the actual USB disk, then it runs through without errors. My workaround involved modifying the three grub-probe lines in the /usr/sbin/grub-mkconfig script to use /cdrom instead of /. The script then ran successfully and generated what looks like the correct grub.cfg. Basically, this changeset: @@ -136,16 +129,16 @@ fi mkdir -p ${GRUB_PREFIX} # Device containing our userland. Typically used for root= parameter. -GRUB_DEVICE="`${grub_probe} --target=device /`" +GRUB_DEVICE="`${grub_probe} --target=device /cdrom`" GRUB_DEVICE_UUID="`${grub_probe} --device ${GRUB_DEVICE} --target=fs_uuid 2> /dev/null`" || true # Device containing our /boot partition. Usually the same as GRUB_DEVICE. -GRUB_DEVICE_BOOT="`${grub_probe} --target=device /boot`" +GRUB_DEVICE_BOOT="`${grub_probe} --target=device /cdrom/boot`" GRUB_DEVICE_BOOT_UUID="`${grub_probe} --device ${GRUB_DEVICE_BOOT} --target=fs_uuid 2> /dev/null`" || true # Filesystem for the device containing our userland. Used for stuff like # choosing Hurd filesystem module. -GRUB_FS="`${grub_probe} --target=fs / 2> /dev/null || echo unknown`" +GRUB_FS="`${grub_probe} --device ${GRUB_DEVICE} --target=fs 2> /dev/null || echo unknown`" if test -f ${sysconfdir}/default/grub ; then . ${sysconfdir}/default/grub -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/703009 Title: grub-probe: error: cannot stat `aufs'. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/703009/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs