Comment 2 for bug 1853812

So, we did observe such an error during the OSP15 hackfest, but that time was during the overcloud upgrade. However, it is worth mentioning that the Undercloud's upgrade job has been broken for the last three releases. When upgrading we do not update the registry in the containers-prepare-paraemters.yaml, therefore we perform the upgrade to the N+1 release with N+1 t-h-t/t-c/t-v packages but N version containers.
Carlos, Mathieu and I are trying to change the job to perform the Undercloud upgrade as is expected.