[MC-53850] Invulnerable item entities and experience orbs are removed client-side when they take damage

The bug

Invulnerable item entities and XP orbs disappear / are removed from the world client-side when they take damage. However, they are still in the world server-side and once the player gets close to them he collects them.

How to reproduce (item)

Summon an invulnerable item entity

/summon item ~2 ~ ~ {Invulnerable:1b,Item:{id:"stone",Count:1b}}

Ignite the block below it with a Flint and Steel and put out the fire afterwards
→ The item is not visible anymore
Move towards the position the item was
→ It is still there and you can collect it

How to reproduce (XP orb)

Place a command block with the following command

/summon armor_stand ~ ~ ~ {Invulnerable:1b,Passengers:[{id:"experience_orb",Value:10s,Invulnerable:1b}]}

Set the top of the command block on fire and put out the fire afterwards
→ The XP orb is not visible anymore
Move towards the position the XP orb was
→ It is still there and you can collect it

Types of damage

Fire
Lava
Cactus

Code analysis

Code analysis by @unknown can be found in this comment.

Attachments

MC-53850.mp4

Comments 40

o1oo11oo 2014-04-27T21:05:34Z

The Item Entity is flagged as Invulnerable in the NBT Tags and therefore should not be affected by the fire, also it does not go away as you said, in the screenshots you can clearly see that the same Item Entity still exists in the world it just isn't getting rendered/shown.

o1oo11oo 2014-04-27T22:37:11Z

I've alwasy considered the Invulnerable Tag as a way to create Entities that can only be damaged by /kill or by the Void, that's why I think the fire should not affect the Item Entity if it's invulnerable. Also, the Invulnerable Tag works like a boolean (but it's TAG_Byte), so anything with Invulnerable:1 is invulnerabe forever. You can confirm that easily by spawning an invulnerable Cow (for example), waiting for a while and then hitting it (you have to be in Survival, because you can damage invulnerable mobs in Creative). I've tested your suggestion anyway and I had the same results like the ones that I put into the report (Item Entity is still there, but invisible when set on fire). So I guess it's not invalid, but either the Item Entity should get deleted, or it should stay visible.

marcono1234 2014-06-08T21:42:17Z

Confirmed for 14w21b

The item stops rendering but can still get picked up

o1oo11oo 2014-06-22T00:03:55Z

MC-51195 happens when you hit a mob with the Invulnerable Tag while you're in creative mode. This happens when you set an invulnerable item on fire. If I set a cow with the invulnerable tag on fire neither does it stop rendering nor does it take damage, it takes no damage at all, no matter if I'm in creative mode or survival mode.

But I've still tested your suggestion Blah and the item stops rendering, no matter if I'm in creative mode or in survival mode. Therefore my report is not invalid.

marcono1234 2014-06-23T18:54:35Z

Blah, stop linking incorrect issues please!

The "Invulnerable" tag says if the item can get killed/destroyed (exeptions: Player in creative/"/kill" command). This is for all kind of damage which means it is not destroyable by lava, fire, tnt, hits, drowning...

First of all, when the item would really get destroyed, it would be incorrect because it should be immune against every kind of damage (with exeptions).
Second like I wrote and the other users here too, you can still pick it up, water makes it visible again and reloading also works to make it visible, so this is neither a duplicate nor invalid.

30 more comments

marcono1234 2014-07-30T17:52:59Z

Confirmed for

14w31a
Minecraft 1.8-pre 1

o1oo11oo 2014-07-30T18:07:54Z

Thanks Marcono1234!

Sonicwave 2014-10-09T04:23:47Z

Confirmed for 1.8. Related to MC-55095.

kasamikona 2014-10-12T13:17:02Z

I can also confirm this for 1.8. This bug has been around for ages! Even before the Invulnerable tag, this could happen due to a lag spike in multiplayer, meaning when you light a fire, it might not actually be there server-side, but client-side the item still gets 'destroyed' even though it still exists. Also sometimes when just touching the side of a lava source block, but not actually being close enough to really burn.

Sonicwave 2014-11-24T01:20:09Z

Confirmed for 1.8.1-pre5.

Tan Chin Cheern 2015-01-04T16:24:06Z

Confirmed for:

-1.8
-1.8.1
-1.8.2 pre-1

trazlander 2015-05-28T04:09:31Z

Confirmed for 1.8.6

Also, related to MC-4438 which is another bug to do with fire turning items invisible.

trazlander 2015-05-28T05:08:46Z

Played with this a bit, pretty positive I know what's going on.

When an item is found to be in fire, it takes an initial hit of 1 damage every game tick, and also lights it on fire which does 2 damage every second. The client is ignoring the Invulnerable tag for the initial fire damage hit and "killing" the item in 5 game ticks when it gets to Health:0. So while the server sees the Invulnerable tag and keeps it alive at 5 health, the client sees it in fire, goes Health:4..3..2..1...and kills it at 0, making it invisible.

Skylinerw 2015-05-28T10:20:32Z

Confirmed for XP orbs as well.

Damage from being within lava (not the fire applied by it) as well as being damaged by a cactus will also cause this issue. Not sure if explosions can.

Upon closer examination, the entity's internal 'invulnerable' value constantly swaps from true to false at all times. Don't quote me on this, but it looks to be that way for all entities. The main difference here is that items/XP orbs catch when 'invulnerable' is false for the client. I personally have no idea why that is other than it maybe being a timing issue, so unfortunately that's as much as I can provide.

o1oo11oo 2015-07-28T16:57:12Z

I tested other types of damage as @unknown mentioned and added them to the description. Also, as it turns out, explosions actually destroy the item/xporb even if it's invulnerable, instead of turning it invisible. Not sure if this is intended, my guess is that it isn't.

132ikl 2016-02-18T04:09:43Z

Confirmed for 1.9 Prerelease 1

marcono1234 2016-02-18T16:36:56Z

Relates to

Please link to this comment in the description of the report.

The following is based on decompiled version of Minecraft 1.8 using MCP. All method and class names are the names used in the decompiled version.

There are two reasons why this happens. The first one is that the client does not know that the item or in general any entity is Invulnerable (this is because none of the packets send to the client contain this information, see also MC-72774 and MC-88181). The second bug is that the public boolean attackEntityFrom(DamageSource source, float amount) of the net.minecraft.entity.item.EntityItem class acts server- and client-side, which is why the fact that the client does not know that an entity is Invulnerable matters. Other classes like the net.minecraft.entity.EntityLivingBase class only run this method server-side.

marcono1234 2016-02-18T16:40:40Z

Please update the provided command as it currently does not contain the Item tag

/summon Item ~3 ~ ~ {Invulnerable:1b,Item:{id:"stone",Count:1b}}

o1oo11oo 2016-02-18T16:55:34Z

I added the link to your comment @unknown, but is the item tag necessary to summon the item? It doesn't really matter if the entity is a stone block or a grass block, 5 blocks or 10. Unless summoning items without an Item tag doesn't work anymore or is going to be deprecated in the future I don't really see why you'd specify it just for testing this (just tried it, without the Item tag still works in 1.9-pre1).

marcono1234 2016-02-18T18:02:10Z

It works but it constantly prints the error message described in MC-11834

o1oo11oo 2016-02-19T12:20:05Z

Didn't know that, changed the command

Étienne B. 2016-07-14T00:19:15Z

Confirmed for 1.10.2

PhiPro 2017-03-25T23:34:29Z

Apparently, the Invulnerable tag is not synced to the client.
For mobs, attackEntityFrom(DamageSource source, float amount) checks whether it is called from the client which is why they aren't killed on the client. However, this check is missing for Items and XPOrbs.
There are some other things going on, which actually cause dealFireDamage() to be called on the client for Items but not mobs.
Anyway, adding the check fixes the problem.

I can't reproduce explosions killing the item. Maybe, they just turned invisible and got pushed away, so you couldn't pick them up?

Edit: Apparently, that's what @Marcono1234 already found out; missed the comment

CreeperMagnet_ 2018-06-29T20:29:52Z

This issue is still present in 1.13-pre5.

Please keep your issues updated.

CreeperMagnet_ 2018-07-05T17:22:55Z

Affects 1.13-pre6.

Please update the experience orb example to

/summon armor_stand ~ ~ ~ {Invulnerable:1b,Passengers:[{id:"experience_orb",Value:10s,Invulnerable:1b}]}

As the xp_orb id changed.

Chandler 2020-09-01T21:52:40Z

Please stop posting random comments that are not relevant to the reports that you are commenting on Mateus.

Ely G 2020-10-13T16:52:09Z

Affects 1.16.3. Also, this happens to non invulnerable entities that take damage for more than 5 ticks. One can observe this by summoning an item, changing its Health to 1000s, and setting it on fire for about a second or two.