[MC-89923] No AI Mobs from Natural Mob Spawners

After starting a world in creative, I had happened to spawn next to a dungeon. After entering, I noticed a massive amount of Skeletons floating about, and they're even spawning in sun light. I'm unable to hurt them more than once.

Linked issues

is duplicated by 39

MC-89925 skeleton spawner under sand spawns mobs that don't die or move Resolved

MC-89966 Zombie spawner spawns chicken at higher light level Resolved

MC-90069 Invisible baby zombies riding chickens from spawner Resolved

MC-90114 Floating Mobs Coming From Spawner Resolved

MC-90136 15w41b Dungeon Spawner Desert Resolved

34 more links

relates to 4

MC-90001 Hostile mobs on peacefull Resolved

MC-88646 Spider Jockeys are broken - skeleton does not move Resolved

MC-90101 Mob Spawner is overwriting (ignoring?) Pos[x,y,z] data of entity Resolved

MC-91290 Skeletons with no AI spawning naturally Resolved

Attachments

Comments 24

[Mod]Les3awe 2015-10-07T15:37:48Z

Confirmed

[Mod]Les3awe 2015-10-07T15:38:31Z

This issue relates to MC-88646

Ditto Slash 2015-10-07T17:03:50Z

No AI mobs from ALL natural spawns, it seems...?

Jaqi Hegland 2015-10-08T02:00:44Z

I came here because of a Skeleton that doesn't react, and I'm pretty sure that spawned outdoors at night. I hit it once, then could not affect it again. I dug all the dirt out from underneath it and it didn't fall. Seems like the same issue.

I have found, fought, killed and been hurt by other monsters near here. It's not all the monsters in the world, but it has been a couple.

Tyler Blake 2015-10-10T11:19:15Z

I've come across this bug in my hardcore world. I found a spider dungeon, looted the chests, and when I turned around there were several floating skeletons. Once I managed to push my way through them, I looked back and saw that more were constantly spawning.

14 more comments

Irbis 2015-10-10T11:54:15Z

It might be related to https://bugs.mojang.com/browse/MC-90101

Anomie X 2015-10-10T13:21:48Z

It might be related to https://bugs.mojang.com/browse/MC-90101

That seems unlikely.

What appears to be going on is that spawning of entities with passengers is screwed up. For example, when the spider spawner is lit it will be trying every tick to spawn spiders, but none of these spiders will be able to spawn because of the light levels. 1% of these spiders, however, will be skeleton jockeys, and apparently the skeletons wind up being half-placed in the world (there, but not in a way that they'll be ticked or saved) even though the spiders themselves aren't.

It's likely the same can happen when a natural spider jockey tries to spawn. Being able to hit the skeleton once then not again is likely because the one hit sets the temporary invulnerability which never goes away because the skeleton isn't ticked.

Zombie spawners seem similar but different: chicken jockeys will spawn the chickens, while the baby zombies will not be correctly added to the world but will be saved. Logging out and back in results in these babies being properly added to the world. The difference is probably because here the zombies (rider) are spawned first then the chicken (mount) is added, while for the skeletons it's the spider (mount) that's spawned first then the skeleton (rider) is added.

Irbis 2015-10-10T13:40:21Z

@Anomie X, now i see. Thx for explanation.=]

XLizardGamingX 2015-10-12T12:14:51Z

They also spawn in peaceful mode, and when you run /say @e[r=5], it says Username and skeleton.

philippe m 2015-10-13T15:11:46Z

i dont see why my ticket got a duplicate from here...its not even the same bug... might be related but its not the same thing at all
ok now i just checked and my zombie sapwner is empty too...

Jeff Staub 2015-10-13T18:37:11Z

I am seeing this behavior in snapshot 15w41b. Skeletons appearing around a spider spawner.

SunCat 2015-10-13T19:00:47Z

Jeff, this bug was first found in this (15w41b) snapshot, already confirmed and will be fixed in future version.

WesselH 2015-10-14T19:06:26Z

I am not sure, but I think it still exists in 15w42a. Or at least something similar is happening in 15w42a.

[Mod] redstonehelper 2015-10-14T19:07:04Z

WesselH: Screenshots (with the F3 screen) and steps to reproduce, please.

Ernest Wrighton 2015-10-22T02:50:18Z

Hmmm...

WesselH 2015-10-22T17:34:09Z

Looks like its fixed in 15w43a/b

WesselH 2015-10-22T18:05:17Z

I also can't find a "dead" skeleton anymore in 15w42a

Warren Liddell 2015-10-23T09:53:19Z

This error is occuring on 42a .. however im testing to see how it goes on 43b

bob 2015-10-23T17:15:38Z

In 43b there was a no AI skeleton that spawned, albeit naturally

Bob Saggot 2015-10-25T08:44:21Z

I encountered one skeleton with no AI, but it spawned naturally as well. I managed to hit him once, then he froze.

John Walter 2015-10-25T16:35:58Z

Attached image 2015-10-25_03.09.31.png is on 43c. I'm thinking this isn't really fixed yet. Hit this skeleton once, then he froze.

SunCat 2015-10-25T16:44:22Z

@unknown and @unknown, were your worlds opened in any version before 15w42a? Because if they were, the NoAI skeletons could spawn and stay there until you found them in this version, or it's actually a different bug.

John Walter 2015-10-25T21:25:19Z

SunCat, yes, I've been updating this world for each snapshot, so the world was open in an earlier version. That being said, I was quite far away from this area, so I believe it was a fresh natural spawn. I say "believe" because I'm not certain. After quitting Minecraft, the skeleton is no longer there when I reopen the game. This could definitely be a separate issue, or already fixed. I'll keep watching to see if it happens again.

[Mod] redstonehelper 2015-10-25T21:26:50Z

If you find new information, please comment here: MC-91290