MOTD display updates can be applied though none is actually available

A few days ago I upgrade my home server from ubuntu 21.04 to 21.10 using do-release-upgrade.

The install brokes during the process, but I think I was able to repair (thanks to other posts from here).

However, I have an inconsistent behavior.

The MOTD says I have 470 upgrade that can be applied immediately.

It suggest to run apt list --upgradable, but this command tell every thing is up to date.

What's wrong? how to fix?

If it helps:

sudo run-parts /etc/update-motd.d/
cat /run/motd.dynamic.new

Outputs:

Welcome to Ubuntu 21.10 (GNU/Linux 5.13.0-21-generic aarch64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

 * Super-optimized for small spaces - read how we shrank the memory
   footprint of MicroK8s to make it the smallest full K8s around.

   https://ubuntu.com/blog/microk8s-memory-optimisation

470 updates can be applied immediately.
To see these additional updates run: apt list --upgradable

sudo apt list --upgradableoutputs Listing... Done

sudo apt update :

Hit:1 http://ports.ubuntu.com/ubuntu-ports impish InRelease
Hit:2 http://ports.ubuntu.com/ubuntu-ports impish-updates InRelease
Hit:3 http://ports.ubuntu.com/ubuntu-ports impish-backports InRelease
Hit:4 http://ports.ubuntu.com/ubuntu-ports impish-security InRelease
Hit:5 https://apt.syncthing.net syncthing InRelease
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.

uname -a outputs

Linux homeserver 5.13.0-21-generic #21-Ubuntu SMP Tue Oct 19 09:01:50 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

And finally, lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 21.10
Release:        21.10
Codename:       impish

Ok, I missed an important part in my diagnostic.

sudo run-parts /etc/update-motd.d/

Outputs also (missed the latest lines in my copy/paste)

/etc/update-motd.d//90-updates-available: 7: /usr/share/update-notifier/notify-updates-outdated: not found run-parts: /etc/update-motd.d//90-updates-available exited with return code 127

This lead to this post.

Basically, a package was missing (not sure to get why this was missing).

As the other post stated, running sudo apt install update-notifier-common solved the issue.