Comment 10 for bug 1904580

> Charms were not upgraded while this broke. We simply upgrade the packages.

If that's the case, package maintainer script might be related? For example,

$ grep /var/lib/nova /var/lib/dpkg/info/nova-common.postinst
            --home /var/lib/nova \
        chown -R nova:nova /var/lib/nova/
    find /var/lib/nova -type f -exec chmod 0644 "{}" + -o -type d -exec chmod 0755 "{}" +
    find /var/lib/nova -name "console.log" -exec chmod 0600 "{}" +
    find /var/lib/nova -name "console.log" -exec chown root:root "{}" +