Comment 4 for bug 1716927

I had the same issue but with different containers - a different container would report "Failed to update apt cache" after consecutive runs.

For me, I found that I was running out of disk space. It's been a while since I've worked with Ubuntu and doing an "Guided" disk partition method was the wrong way to go. Ubuntu creates a small / partition with the large majority of disk allocated to /home

Because OpenStack-Ansible creates the containers under /openstack, you can quickly run out of space and not have enough room for updates of packages from apt - thus giving us the error.

Moving to Pike may have created a false fix in that either you rebuilt the servers thus removing the /openstack directory, or manually deleting lxc containers did the trick.