[MC-16191] When the world loads skeletons it crashes

Put the summary of the bug you're having here

What I expected to happen was...:
The game operate normally

What actually happened was...:
Game loaded as normal, got into my world and within 30 seconds crashed. Have a skeleton spawner near my house which may be triggering it.

Steps to Reproduce:
1. Load a world(Possibly with a skele spawner)
2. Wait for crash

Linked issues

is duplicated by 30

MC-16241 Game randomly crashing Resolved

MC-16295 chunk errors random crashes and other Resolved

MC-16369 Something with spawners Resolved

MC-16371 Crash with MobSpawners Resolved

MC-16404 NPE for no reason Resolved

25 more links

relates to 1

MC-16290 [crash] mob spawner crashing game Resolved

Attachments

Broken Spawner Test World.zip

crash-2013-05-23_16.04.57-client.txt

crash-2013-05-31_10.10.15-client.txt

crash-2013-05-31_10.38.18-client.txt

crash-2013-05-31_20.53.26-client.txt

crash-2013-05-31_21.39.31-client.txt

Fireproof Zombie.schematic

Mob with Status Effects.schematic

Comments 14

Tails 2013-05-23T17:45:31Z

Please attach the crash report, otherwise this ticket is incomplete.

Brian Lyall 2013-05-23T22:05:43Z

Alright, added the crash report

Tails 2013-05-23T23:56:31Z

Note:

Description: Loading entity NBT

java.lang.NullPointerException
	at np.a(SourceFile:357)
	at nq.a(SourceFile:251)
	at sz.a(SourceFile:297)
	at mx.f(SourceFile:1061)
	at aas.a(SourceFile:116)
	at aas.h(SourceFile:234)

Nathan Adams 2013-05-24T09:15:22Z

You have an effect ID on a mob that doesn't exist in the game.

solal2003 2013-05-25T15:23:13Z

Dinnerbone said it all, the map that you probably need a mod

4 more comments

Brian Lyall 2013-05-26T02:01:39Z

Yep, but no mods have been used on this map, this has been purely snapshots

WolfieMario 2013-05-31T15:20:36Z

Dinnerbone, are you sure? My friends and I have been getting this crash for any Effect ID - including ones that the code says are still correct. It seems changes thanks to the Attributes system have broken spawners' ability to apply any effects to mobs. I've attached a schematic with Invisibility, a vanilla effect ID, which still causes crashes in the snapshots. This spawner causes no issues in 1.5.2.

Mateus Salviano 2013-06-01T00:07:08Z

This attachment is the crash report I got after loading a world with a spawner that spawns a zombie with custom effects, I made this spawner back in 1.4 (if I'm not wrong) and it worked fine until 1.5.2, in fact, I tested it in 1.5.2 a minute before 13w22a and it worked just fine, spawning the mob without troubles and all. However now in 13w22a, it just needs to exist in the world and it crashes on the moment you load the save.

My minecraft is mod-free and totally original, nothing that could be caused by external environment.

WolfieMario 2013-06-01T02:05:32Z

Mod Tails, can you please re-open this? I have attached a test world which works perfectly fine with Minecraft versions up to and including 13w19a. When used on 13w21a+, the game immediately crashes with the above report. Note that 13w21a was the version where several potion effects were adjusted to interact with the Attribute system.

At least 13 other peoples' valid reports have been closed as duplicates of this report, and this report has erroneously been marked as "Invalid". There are at least 16 people, myself included, actively effected by this bug, and it can't be fixed if every single report about it gets closed like this. This bug has been by no means "resolved", and whether or not this particular ticket is "Invalid", at least 14 other tickets on this bug are valid and have been marked as duplicates of an Invalid ticket.

I'd like to make this clear, as it's evident that there has been some sort of misunderstanding here:

Spawners with the ability to spawn mobs with potion effects are a vanilla Minecraft feature which have been around ever since SpawnData was first introduced. They have not caused crashes until 13w21a created a dependency between Potion Effects and Attributes. No changes were made to the NBT format, and for all intents and purposes, a spawner which functioned correctly should not have been broken by 13w21a. However, the game makes the assumption that a mob has all of its Attributes intialized before de-serializing ActiveEffects NBT data. As this assumption is incorrect for mobs produced by spawners, a NullPointerException occurs. This makes it impossible for spawners to apply potion effects to the mobs they spawn, breaking countless adventure maps, among other things, and removing a powerful feature from Vanilla Minecraft. The correct way to achieve this effect has not been changed: it has been broken by a bug. None of this has anything to do with using invalid potion effect IDs.

Steps to Reproduce:

Load the attached world in 13w19a or earlier.
Observe that the spawner spawns zombies with Fire Resistance. Feel free to spleef them into lava to confirm that it works.
Save and exit.
Now load the world in 13w21a or later - my personal test was on 13w21b, but it should work on any version older than these.
Observe that a moment after terrain loads, before the zombie spinning in the spawner cage even has a chance to load, the game crashes.
Compare this crash report to the 17+ other crash reports people have posted, and see that they are essentially the same.

Elf Elf 2013-06-03T19:58:39Z

Try removing any UUIDLeast and UUIDMost tags from SpawnData and any Properties tags in SpawnPotentials.

WolfieMario 2013-06-03T20:05:43Z

This problem is not related to UUIDLeast/Most - in the test world, these properties are not defined in SpawnData at all, and SpawnPotentials are not defined at all either.

Also, if you remove the Properties tag from SpawnPotentials, the mob cannot have custom properties at all - the game will generate a blank Properties, which will overwrite SpawnData and blank it after your first spawn. If you do this, you won't have potion effects, or anything at all, after your first spawn. If you do not have SpawnPotentials at all, the game will automatically create SpawnPotentials from the existing SpawnData, meaning that doesn't work either.

If you wanted to avoid crashing, you could just as easily remove ActiveEffects, which is the actual cause of the crash. The problem is, once again, this workaround removes the potion effects on your mobs - none of these workarounds lets you keep your worlds compatible with the future snapshots and still have potion effects on spawned mobs.

EDIT: I have attached the schematic used in my test world. You can observe that it does not have any of the tags you told me to remove, and still causes crashes on 13w21a+.

Elf Elf 2013-06-03T20:14:08Z

Confirmed, the crash is being caused by correctly-formed, vanilla ActiveEffects.

Daniel "Glampkoo" 2013-06-03T23:29:53Z

Duplicate of MC-17222

J Robb 2013-06-26T03:55:05Z

No, horse spawners without ActiveEffects still crash the game. They cause a crash if they have SpawnData or SpawnPotentials. Also, that was filed later, so if anything it would duplicate this.