I am also having the same issue. I just updated to 6.12.1.
My cache drive has plenty of room. I can't create new docker containers.
The Error I receive when installing the docker.
docker: Error response from daemon: failed to start shim: symlink /var/lib/docker/containerd/daemon/io.containerd.runtime.v2.task/moby/188f4efc137e795b0291fc2f1f613e04f0bcb7de1933f3da68f6bf8840c45c63 /var/run/docker/containerd/daemon/io.containerd.runtime.v2.task/moby/188f4efc137e795b0291fc2f1f613e04f0bcb7de1933f3da68f6bf8840c45c63/work: no space left on device: unknown.
In the unRaid logs it looks like the docker network is blocking a port for some reason.
Jun 23 10:41:57 unRaid-Plex kernel: docker0: port 6(veth9051fe0) entered blocking state
Jun 23 10:41:57 unRaid-Plex kernel: docker0: port 6(veth9051fe0) entered disabled state
Jun 23 10:41:57 unRaid-Plex kernel: device veth9051fe0 entered promiscuous mode
Jun 23 10:41:57 unRaid-Plex kernel: docker0: port 6(veth9051fe0) entered disabled state
Jun 23 10:41:57 unRaid-Plex kernel: device veth9051fe0 left promiscuous mode
Jun 23 10:41:57 unRaid-Plex kernel: docker0: port 6(veth9051fe0) entered disabled state
What make and model did you get? I'm currently having a bear of a time with my Samsung SSDs and even got a newer Samsung that is also giving these errors.
I also have installed a GPU and am receiving these errors, but my issue is only on boot for the PlexInc Docker. Typically I can manually restart the docker and it will boot fine, but it seems CA Backup/Restore might be causing some issue for me or it just makes the issue more prevalent.