[MC-274223] Attributes with same ID don't stack when wearing armor

Same problem as MC-16466 but with IDs instead of UUIDs. Even the "Armor", "Armor Toughness", and "Knockback Resistance" attributes are effected. But if you use armor from the creative menu or craft the armor in survival, the attributes stack.

Linked issues

relates to 1

MC-16466 Attributes with same UUID don't stack when wearing armour Resolved

Comments 2

[Mod] ManosSef 2024-07-07T14:21:27Z

Vanilla armor does not use different attribute modifiers for each piece, but only one merged modifier which changes dynamically, which is why it stacks. By design, just like with the UUID system before 1.21, attribute modifiers with the same ID do not stack. The 24w21a changelog implies this behavior too:

Using the same ID for different modifiers is allowed as long as the modifiers are for different attributes

violine1101 2024-07-07T14:39:20Z

To my knowledge, for enchantments the game suffixes each attribute modifier ID with the slot the item is in so that the same enchantment can stack for multiple pieces of armor in different slots.

But in general it's intentional that attribute modifiers with the same ID do not stack as outlined in the changelog. It's the same as the UUID system before, just that it now uses a resource location instead because that's easier to work with.