I’m glad you guys are working hard on such gorgeous product like Hestia! We are all human and some error can happen now and then…
I’d recommend to perform system backup prior to upgrading any huge SW bundle, ie. CPs, especially in case of ex-post custom configuration.
Basically any diff based backup tool can perform well here.
I am using Duplicati with the following folder filter:
-/dev/
-/lost+found/
-/media/
-/mnt/
-/proc/
-/run/
-/sys/
-/tmp/
Duplicati works well even on VPS. With numerous cloud support it is enough to find some cloud provider offering at least the same size as your disk and you are good to go.
In case of any disaster, one can easily install previous OS (proper version) and restore OS backup followed by this guide or burning this iso.
Edit: Eventually created this tuto - maybe someone will find it useful. Edit if needed. Was a quick one. Thanks.