Latest log from 13.20.0.2307 test enviroment https://pastebin.com/fkSNbzqC

Outline: All damage sources do durability damage to armor.

Research:
I noticed a couple of mods had situations in which they were damaging player armor and so reported these to the mod authors. (in particular Tough as Nails and Blood Magic)
Both active authors told me that they used DamageSource.generic which makes use of bypass armor.

Out of a hunch I thought that it may be a forge bug.

So I tested by creating minecraft profiles with forge installed from 1.8 through to 1.10
When I noticed that these all complied with bypass armor I started testing 1.11 forge versions.
I tried a great deal of different versions until I pinpointed the issue starting in 13.20.0.2307. The bug affects all versions greater than it.

The test method was to
1.create a world.
2.equip a set of armor
3.throw a instant damage potion at my feet.

I did this with each forge version I tested until I pinpointed its origin at 13.20.0.2307

Note: This also occurs some time into 1.12 but is fixed by 14.21.1.2413 I have not thoroughly tested the 1.12 forge versions.
Edit: I pinpointed the 1.12 fix of this issue to 14.21.1.2394 by using the above method.

Edited July 15, 20178 yr by Rorax

See https://github.com/MinecraftForge/MinecraftForge/issues/3933

11 hours ago, quadraxis said:

See https://github.com/MinecraftForge/MinecraftForge/issues/3933

I'm not sure what you want me to see here? I am aware that it was fixed for 1.12 by talandar. But the bug still exists in 1.11.2 where it came from.

I am perfectly willing to backport small fixes like this to older versions, as long as they are fixed in the latest version first.

I have pushed a fix for this in Forge for 1.11.2.

4 hours ago, diesieben07 said:

Update to 1.12 then? I am not sure if such non-world-breaking bugs will still be fixed for 1.11.x.

Its not game crashing no. But it is game ruining yes. Losing your armor to non armor damages is quite game breaking in many standard play aspects. And had it been detected earlier by someone and not me 94 versions later you wouldn't be so facetious. On top of that 1.11.2 is still a supported version soooooo