Comment 4 for bug 1696124

This actually is on a plano device (stlouis) where I'm hitting the problem, and it does have that in /etc/netplan/00-default-nm-renderer.yaml. It does not seem to depend on a lot of snaps being refreshed at once, as mentioned before, I can reproduce it with just 'sudo snap refresh network-manager --ignore-validation && sudo snap install <something>" Anything can be used for the install snap, even hello. As a quick way of reproducing, something like this script should get you there (in this case, I'm flipping between edge and stable since there are different versions of nm in each - it ran about all the way through about twice for me before hitting the error):
#!/bin/bash
set -ex
while [ 1 ]; do
    sudo snap refresh --edge network-manager --ignore-validation && sudo snap install hello && sudo snap remove hello
    [ "$?" != "0" ] && break
    sleep 1

    sudo snap refresh --stable network-manager --ignore-validation && sudo snap install hello && sudo snap remove hello
    [ "$?" != "0" ] && break
    sleep 1
done

Here are the last 100 lines of syslog from when I was running the script above and saw it reproduced: https://paste.ubuntu.com/24866493/