There should be a way to do maintenance in a safe way. This means to test upgrades, patches, changes and similar things in a shop clone/copy, then to synchronize that copy with the public shop. This also reduces shop downtime, as synchonization can be done with a script, reducing customer distraction.
I wrote more on this in the forum and will come up with patches there soon:
https://forum.thirtybees.com/topic/76/safe-maintenance-strategy-shop-cloning