On Tue, Oct 06, 2020 at 02:58:22PM +0200, Matteo Croce wrote: > The official Debian Buster image breaks when upgrading to bullseye. > GRUB fails like: > > error: symbol 'grub_file_filters' not found. > Entering rescue mode... > grub rescue> > > I see the error in the HyperV graphic console, > I could probably recover it if only GRUB uses the serial for IO.
This is likely the same underlying issue as the one described in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=966575 The issue is likely that the MBR code on your instance was not updated with the grub package upgrade due to block device differences between the environment in which grub originally configured the drive MBRs and the environment in which the upgrade ran. The workaround would be to to use grub-install to write the updated MBR code to the correct block device. Naturally you need to do that before you reboot. If you've already rebooted and need to recover, you'd need to boot some kind of recovery environment (possibly involving launching another VM and attaching the relevant block device to it). I don't know that there's anything we can do in the cloud images specifically to help with this situation. noah
