Symptoms
Disk space usage on /mnt/boot exceeds 75% not allowing any upgrades or patching to happen on the Firewalls managed by the FDM.
Diagnosis
When the disk space on the NGFW itself exceeds 75% in the /mnt/boot directory upgrades are not allowed.
Solution
Do this at your own risk but I have run it on several 2110s and 2130s and it seems to work fine.
SSH into the NGFW.
connect to FTD if not already connected and run the command "show version system"
Note the system image file. This is the current image in use
Now enter Expert and sudo su -
cd /mnt/boot/installables/switch
ls -al and remove older year files
in my case I rm all 2017 and 2018 files leaving my 2019 - 2021
