Q:

Ubuntu 16.04 latest update broke Docker (docker-ce)

I run Ubuntu 16.04 on my desktop. I use docker-ce and it has been working up until a few days ago. The auto-update in Ubuntu seems to have broken it.
robert@catness:~$ docker ps
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

I tried following the instructions at https://docs.docker.com/install/linux/docker-ce/ubuntu/ to remove and reinstall but it hasn't worked.
robert@catness:~$ sudo apt-get install docker-ce
Reading package lists... Done
Building dependency tree       
Reading state information... Done
docker-ce is already the newest version (5:18.09.0~3-0~ubuntu-xenial).
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies.
 docker-ce : Depends: containerd.io but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

I believe the issue is with containerd.io. The command sudo apt-get -f install tries to install it and this errors:
The following additional packages will be installed:
  containerd.io
The following NEW packages will be installed
  containerd.io
0 to upgrade, 1 to newly install, 0 to remove and 1 not to upgrade.
1 not fully installed or removed.
Need to get 0 B/19.9 MB of archives.
After this operation, 87.6 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
(Reading database ... 523620 files and directories currently installed.)
Preparing to unpack .../containerd.io_1.2.0-1_amd64.deb ...
Unpacking containerd.io (1.2.0-1) ...
dpkg: error processing archive /var/cache/apt/archives/containerd.io_1.2.0-1_amd64.deb (--unpack):
 trying to overwrite '/usr/sbin/runc', which is also in package runc 1.0.0~rc2+docker1.13.1-0ubuntu1~16.04.1
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/containerd.io_1.2.0-1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

There was some problem with /usr/sbin/runc, as part of debugging I tried deleting the file there, but this has made no difference at all:
robert@catness:~$ ls /usr/sbin/runc
ls: cannot access '/usr/sbin/runc': No such file or directory
robert@catness:~$ sudo ls /usr/sbin/runc
ls: cannot access '/usr/sbin/runc': No such file or directory

Does anyone have any suggestions as to what I should do next to investigate this issue.

A:

I'd remove the runc package. The docker1.13.1 version is a pointer to a very old and unsupported version of docker, so this is likely left over from a past upgrade. Then you should be able to install containerd.io.
You may have to remove the docker-ce package first using apt-get remove docker-ce and then execute your apt-get remove runc then to install docker-ce again you have to use apt-get install docker-ce. This is because trying to remove runc without first removing docker-ce does not work
Let me know if that's successful as I'd like to open an issue in docker for this if one doesn't already exist.

