In this particular case I did a no-op upgrade from 1.5.5 not realizing I was already upgraded but proceeded with the reboot anyway.
It rebooted fine but I noticed my user containers weren’t started and docker ps -a just hung. I tried sudo system-docker restart docker and that didn’t help either. The issue resolved itself over the next 10 or so minutes and now the daemon magically responds.
I’ve bumped into similar issues a few times now. Actually, almost every time I’ve done an upgrade or even reboot without upgrading. Sometimes it is system-docker that gets stuck, so I can’t even SSH in for about 10 minutes or so til it decides to work. It’s usually faster to provision a new machine.
Is there anything I can do to help diagnose this? Has anyone else experienced this?