More information needed for failed "Verify that the workload of <charm> has been upgraded on units"

[samuelallan72]

An example attempted upgrade output:

Running cloud upgrade...
Verify that all OpenStack applications are in idle state ✔
Back up MySQL databases ✔
Archive old database data on nova-cloud-controller ✔
Verify that the workload of 'ceph-mon' has been upgraded on units: ceph-mon/0, ceph-mon/1, ceph-mon/2 ✖
2024-07-08 07:51:56 [ERROR] Unit(s) 'ceph-mon/0, ceph-mon/1, ceph-mon/2' did not complete the upgrade to wallaby. Some local processes may still be executing; you may try re-running COU in a few minutes.
2024-07-08 07:51:56 [ERROR] See the known issues at https://canonical-charmed-openstack-upgrader.readthedocs-hosted.com/en/stable/reference/known-issues/

It would be helpful if cou pointed the user to:

• why it failed the check (as in specifically why - eg. "apt update showed victoria sources when wallaby was expected")
• helpful information to begin debugging. I tried re-running COU after a few minutes, but same result.