I have a regular backup job that uses incus file pull to retrieve a couple of files from within a container to the host, which is running Ubuntu focal (20.04), and incus from the zabbly repository.

Judging from the logs, three days ago (2025-01-26), incus upgraded from 1:6.8-ubuntu20.04-202412192307 to 1:6.9-ubuntu20.04-202501241740 and subsequently the backup job failed. It appears the reason is that incus file pull ceased working after the upgrade. I spent a while figuring out if the reason was some other change within the container, but it turns out that file pull no longer works with any other container on the system either, including freshly launched ones. For example:

root@leela:~# incus launch images:ubuntu/noble/cloud filetest
Launching filetest
root@leela:~# incus shell filetest               
root@filetest:~# echo foo > foo
root@filetest:~# 
logout
root@leela:~# incus file pull filetest/root/foo .
Error: error receiving version packet from server: server unexpectedly closed connection: unexpected EOF

I've tried this with several different containers running focal, jammy, and noble, all producing the same error. Incidentally, incus file push fails with the same error too. Has there been a change in file handling between these versions?

Looking through the changelog, #1592 seems a possible culprit but seems specific to file pull (would it affect file push too? I haven't checked the logic to see if it's built on the same basis).