I ran into this issue with ubuntu instance reboot both while rebooting with API and in-guest reboot command.
From the serial console, I could see that the guest failed to make any progress at this point when I did sudo reboot:
[ OK ] Stopped Update UTMP about System Boot/Shutdown.
[ OK ] Stopped Network Time Synchronization.
[ OK ] Stopped Create Volatile Files and Directories.
[ OK ] Stopped target Local File Systems.
[ OK ] Stopped target Mounted snaps.
Unmounting /boot/efi...
Unmounting /run/snapd/ns/lxd.mnt...
With instance reboot API, it got stuck at start up instead:
[ OK ] Started Session 1 of User ubuntu.
[ 301.807462] cloud-init[1378]: loading tables: 2 for warehouse: 10
[ 302.097101] cloud-init[1378]: loading tables: 2 for warehouse: 9
Starting Download data for…led at package install time...
[ OK ] Finished Download data for…ailed at package install time.
Starting Time & Date Service...
I ran into this issue with ubuntu instance reboot both while rebooting with API and in-guest reboot command.
From the serial console, I could see that the guest failed to make any progress at this point when I did
sudo reboot:With instance reboot API, it got stuck at start up instead: