Affected Versions (Do not use "latest")::

• ArmorPlus: armorplus-1.12.2-11.14.0.42.jar
• TheDragonLib: thedragonlib-1.12.2-5.3.0.jar
• Minecraft: 1.12.2
• Forge: forge-2770.jar
• (Optional) Just Enough Items (JEI): jei_1.12.2-4.13.1.220.jar
• (Optional) Tinkers' Construct: TConstruct-1.12.2-2.10.1.87.jar
• (Optional) CraftTweaker (CrT): CraftTweaker2-1.12-4.1.11.jar

Affected Side (Client or Server):

• Client
• Server

What happens:
Once full Ultimate Armor is equipped it crashed the client but not the server, and corrupts the player file.
Tested on all other armor types and no issues.

What you expected to happen::
No Crash

If its a crash, post your crash report (via. pastebin/gist/etc):
https://pastebin.com/JCgSqqYb

Your configuration files from config/armorplus/ (registry.cfg mainly):
https://pastebin.com/fRWfhyaU

(Optional) Mod List:
300+ mods (PO3 Development)

Will investigate, my apologies for the late response.

happens on armorplus-1.12.2-11.15.1.44.jar too

Just realized the issue. Cazador have you added/changed anything about the ultimate armour ? It seems like it's effects don't have the respective number of properties
For each effect added there must be a duration and an amplifier line added. There might be one effect more config/armorplus/registry.cfg/