Sysupgrade ubus error when running over SSH

Hello,

In my build system I'm trying to have the image I built programmatically deployed.
I can upload the new image with scp and run the sysupgrade with ssh but when I do so, right after the expected closing of the session, I get:

verifying sysupgrade tar file integrity
Mon Mar 31 23:34:33 CEST 2025 upgrade: Saving config files...
Mon Mar 31 23:34:34 CEST 2025 upgrade: Commencing upgrade. Closing all shell sessions.
Command failed: ubus call system sysupgrade { "prefix": "\/tmp\/root", "path": "\/tmp\/openwrt-mediatek-filogic-glinet_gl-mt3000-squashfs-sysupgrade.bin", "backup": "\/tmp\/sysupgrade.tgz", "command": "\/lib\/upgrade\/do_stage2", "options": { "save_partitions": 1 } } (Connection failed)

Is this ubus error... normal?

Thank you.

I had this error or a similar one in the past, but the sysupgrades were deployed successfully. Did it work out for you or did it fail?