Hyper-V VM fails with grub rescue shell + kernel panic about gns3-vm HOT 3 CLOSED

I managed to solve this by repairing grub. Here's what you need to do in order to repair grub and get your GNS3 Hyper-V VM booting normally again:

Download Debian Live standard iso Add a new DVD-device to your VM, link it to the Debian Live iso and change the boot-order to CD first. Make sure that your VM has internet connectivity (via Default switch).

Command sequence:

sudo -i
apt update && apt install grub
mount /dev/sda1 /mnt
mount /dev/sda15 /mnt/boot/efi
mount --rbind /dev /mnt/dev
mount --rbind /proc /mnt/proc
mount --rbind /sys /mnt/sys
chroot /mnt
grub-install /dev/sda

It is necessary to re-mount /dev, /proc and /sys from the readonly live system to /mnt. Grub will otherwise fail with "cannot find a device for /boot (is /dev mounted?)" error.

Stop the VM after this, remove the CD/DVD or change the boot order to IDE first. Then restart the VM.

from gns3-vm.

In the end, repairing grub did not work out for me (boot issue remains). Here's what I did instead:

Overwrite 'GNS3 VM-disk001.vhd' (GNS3 system partition) with an untouched copy from the GNS3 VM zip-file. Start an administrative Powershell, change working directory to your VM path and issue the following command:

$VMId = get-vm 'GNS3 VM' | Select-Object VMID -ExpandProperty VMId
icacls '.\GNS3 VM-disk001.vhd' /grant "$($VMId.Guid):F"

The icacls command will grant the replaced vhd read/write access and register it with the VM.

Your projects reside in the 'GNS3 VM-disk002.vhd' and will be mounted to /opt/gns3 upon boot. You may now restart your GNS3 VM and reconfigure networking if necessary.

from gns3-vm.

Thanks for the detailed fix. I am not sure why you got into that situation and how we could prevent this to happen for other users. Please let us know if you have an idea. I am closing this for now.

from gns3-vm.