After upgrading the Sophos UTM in my home lab the VM didnt boot anymore. The following message was visible on the console:
The UTM was not accessible with the management ip address.
Steps to get your UTM back to life
1.) Press the “Esc” button during the boot procedure.
2.) Select “Sophos UTM 9.x” and press the “e” button.
3.) Select “kernel” mode and press the “e” button
4.) Put the following command “init=/bin/bash” and press enter.
5.) Now press the “b” key to boot up the UTM.
6.) Navigate to the path “/usr/local/bin” and delete the file “pg92_schemaupgrade”
7.) Reboot the VM and the UTM should be back online.
Why was the update not successful?
After inspecting the dashboard I realized the data disk was fully occupied. Thats why the update was crashing…
The easiest way to expand the partition is to boot with the GParted Live CD.
Lets try the update again…
What about our “storage” partition? Looks fine 
Reminder for myself. Check the data partition before the next update. Even its not a productive system 
Thanks for sharing the above info. This was exactly my issue and deleting the
schemaupgradefile fixed it and allowed me to resync my backup firewall with my primary.I really appreciate you taking the time to write this up and share with the community. Cheers!