I've noticed some not-so smooth upgrades from Develop 159 code to 160 and 161 on Airgrid M5 nodes using the Bullet sysupgrade. I have tried several times with only one out of 4 upgrades gone smoothly as the previous upgrades have done. The nodes never reboot and remain on the same firmware version before upgrade. They also sometimes aren't accessible with the web interface after the procedure. They also do not seem to attempt a reboot. I'm using Chrome, which has a nice upload progress indicator in the bottom left corner of the browser screen, which "seem" to have reached the 100% mark. These are stable RF paths and are over-the air upgrades at remote sites.
I'm able to use Putty to log in and reboot the nodes., which still indicate that they are running the pre-upgrade firmware. Upon further tries, I find that they do upgrade smoothly if I reboot the nodes immediately before performing the upgrade procedure. Maybe a low memory situation? These are units that do not have tunnels or any other services installed.
At any rate, just wanted to fly this up the flagpole and see if anyone else has experienced this before we try to dive into it deeper.