You should "always" delete the whole folder of the addon/library, if you manually update it from a new zip file!
e.g. live/AddOns/CustomAddonName
That's what the addon manager Minion does the same way, for example
Why?
If you just overwrite it, old files/folders will be kept.
This may be no problem, and often it isn't (except folder size increases for no reason and sending the folder to friends or taking screenshot shows old data and makes the error finding process annoying).
But we had it happen that addons had subfolders containing libraries, which got loaded and bugged out then
e.g. live/AddOns/CustomAddonName/libs/LibWhatever
So better delete the complete addon folder and then extract the new updated files completely to live/Addons.
Watchout: if you extract the zip file the zip program might create a new folder with the name of the zip file!
But you ONLY must extract the contents of the zip file to /live/AddOns.
e.g. zip filename "MyAddon1_v2.zip"
Contents:
folder "MyAddon1"
Extracted Wrong:
live/AddOns/MyAddon1_v2/MyAddon1
Extracted correctly:
live/AddOns/MyAddon1
I'd recommand using Minion, the addon manager, to install and update your addons more easily:
Please read this first ebfore installing it as it contains infos what to do how, prepare firewall whitelist, install 32bit version, maybe install to another folder/drive etc:
https://www.esoui.com/forums/showthread.php?t=8082
Officially download (32bit version as mentioned!) the addon manager here:
https://www.minion.gg/
-> It will update itsself after installation, at first run. So do not wonder if that popup shows asking for an update.