do-release-upgrade stuck configuring openssh server

Question

I'm using do-release-upgrade to upgrade from 18.04 to 20.04.

During the process, it found modifications to my ssh_config, and I chose to view the diff.

It displays this on a page with <OK> at the bottom. But I can't exit this to continue the upgrade. My keyboard inputs are being read by a terminal. The screen now looks like this:

You can see a few of my attempts to resume the upgrade (e.g. re-running do-release-upgrade, and trying apt update and apt upgrade)

How can I resume the upgrade?

Update, 1 hour on

Digging around reveals which processes own various lock files, and some interesting processes that are still running, presumably waiting for me to reply <OK> on the screen showing me the ssh_config diff:

matt@ocinara:~$ sudo lsof /var/lib/dpkg/lock
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
dpkg    16341 root    3uW  REG  259,3        0 13658619 /var/lib/dpkg/lock
matt@ocinara:~$ sudo lsof /var/lib/apt/lists/lock
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
focal   14627 root   14u   REG  259,3        0 13902278 /var/lib/apt/lists/lock
matt@ocinara:~$ sudo lsof /var/cache/apt/archives/lock
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF     NODE NAME
focal   14627 root   66u   REG  259,3        0 12328392 /var/cache/apt/archives/lock
matt@ocinara:~$ ps aux | grep -i focal
root     14627  0.2  1.7 480372 140020 pts/0   S    11:00   0:09 /usr/bin/python3 /tmp/ubuntu-release-upgrader-qzt422az/focal --mode=server --frontend=DistUpgradeViewText
matt     19736  0.0  0.0  10964   780 pts/3    S+   12:00   0:00 grep --color=auto -i focal
matt@ocinara:~$ ps aux | grep -i dpkg
root     16341  0.0  0.1  22216 12776 pts/7    Ss+  11:01   0:00 /usr/bin/dpkg --force-overwrite --status-fd 74 --configure --pending
root     17176  0.0  0.3  85264 24040 pts/7    S+   11:01   0:00 /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/openssh-server.postinst configure 1:7.6p1-4ubuntu0.3
root     17188  0.0  0.0   2604  1684 pts/7    S+   11:01   0:00 /bin/sh /var/lib/dpkg/info/openssh-server.postinst configure 1:7.6p1-4ubuntu0.3
matt     19741  0.0  0.0  10964   776 pts/3    S+   12:01   0:00 grep --color=auto -i dpkg

Answer 1

After more reading around, I've got the upgrade running again like this:

sudo kill 14627  # focal upgrade process - see question

This also resulted in the dpkg processes (see original question) from terminating, and the file lock being released. I then tried

sudo apt dist-upgrade

... which told me to do this first:

sudo dpkg --configure -a

This led immediately back to the question about ssh_config, i.e. back to where I was when the upgrade stopped (I suspect I inadvertently hit Ctrl-C).

And then finally (fingers crossed):

sudo apt dist-upgrade

As I write this, I'm now 15% through the upgrade. I'll update this answer later, hopefully from Ubuntu 20.04!

Update It worked - I'm now on Ubuntu 20.04