MCPE-52743Zombies never spawn as cave mobs
Zombies and zombie villagers do not spawn underground on blocks where they would be defined as cave mobs (that is, where they are subject to and contribute to the cave density cap for monsters). They do spawn in caves, but only on blocks that define them as surface mobs. This causes fewer zombies to spawn in caves than there should be, and consequently causes caves to contain more monsters of other types since there is more room below the cave density cap.
Other monsters (creepers, skeletons, spiders, witches, and endermen) are not affected by this issue.
Steps to reproduce:
- Open the attached demo world
MCPE-52743.mcworld.
There is a 16 x 16 spawn floor at Y=6. The blue square you see is aligned above it. This world is configured so that no spawns can occur naturally anywhere but the spawn floor. - Place a bottom slab on the blue block in front of the bottom observer. Command blocks will replicate this across the entire blue square, hence above the spawn floor. This creates the condition necessary to spawn mobs in caves subject to the surface density cap.
- Use the button to teleport to the Testing Room.
- Use the lever to enable mob spawning. Repeating command blocks will start running that test for zombies and zombie villagers every 5 seconds. If they find any, the chat will show them.
- Wait until zombies and/or zombie villagers are found. This shows that these can spawn on blocks that qualify the mob as a surface mob.
- Disable mob spawning.
- Use the Reset button to kill all the mobs that spawned.
- Use the button to teleport back to the surface. Break the slab you placed. This creates the condition necessary to spawn mobs in caves subject to the cave density cap.
- Return to the Testing Room and enable mob spawning.
- Wait as long as you like. No zombies or zombie villagers will spawn.
Important: The ability to spawn monsters in caves subject to the surface density cap is reported as a bug in MCPE-41273. It may be that such spawns are intended in some cases, but if not it will likely be fixed by reducing or eliminating surface monster spawns in caves. If that fix occurs before this problem, the result will be that zombies or zombie villagers will no longer spawn underground at all! Therefore, this issue needs to be fixed before, or in conjunction with, MCPE-41273.
Linked Issues
discovered while testing1
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![[MCPE Mod] Auldrick](../../../data/avatars/users/10122.svg){kind=small}
Created Issue:
Zombies never spawn as cave mobs
Zombies and zombie villagers do not spawn underground on blocks where they would be defined as cave mobs (that is, where they are subject to and contribute to the cave density cap for monsters). They do spawn in caves, but only on blocks that define them as surface mobs. This causes fewer zombies to spawn in caves than there should be, and consequently causes caves to contain more monsters of other types since there is more room below the cave density cap.
Other monsters (creepers, skeletons, spiders, witches, and endermen) are not affected by this issue.
Steps to reproduce:
- Open the attached demo world
There is a 16 x 16 spawn floor at Y=6. The blue square you see is aligned above it. This world is configured so that no spawns can occur naturally anywhere but the spawn floor.- Place a bottom slab on the blue block in front of the bottom observer. Command blocks will replicate this across the entire blue square, hence above the spawn floor. This creates the condition necessary to spawn mobs in caves subject to the surface density cap.
- Use the button to teleport to the Testing Room.
- Use the lever to enable mob spawning. Repeating command blocks will start running that test for zombies and zombie villagers every 5 seconds. If they find any, the chat will show them.
- Wait until zombies and/or zombie villagers are found. This shows that these can spawn on blocks that qualify the mob as a surface mob.
- Disable mob spawning.
- Use the Reset button to kill all the mobs that spawned.
- Use the button to teleport back to the surface. Break the slab you placed. This creates the condition necessary to spawn mobs in caves subject to the cave density cap.
- Return to the Testing Room and enable mob spawning.
- Wait as long as you like. No zombies or zombie villagers will spawn.
Important: The ability to spawn monsters in caves subject to the surface density cap is reported as a bug in
MCPE-41273. It may be that such spawns are intended in some cases, but if not it will likely be fixed by reducing or eliminating surface monster spawns in caves. If that fix occurs before this problem, the result will be that zombies or zombie villagers will no longer spawn underground at all! Therefore, this issue needs to be fixed before, or in conjunction with,MCPE-41273.
Zombies and zombie villagers do not spawn underground on blocks where they would be defined as cave mobs (that is, where they are subject to and contribute to the cave density cap for monsters). They do spawn in caves, but only on blocks that define them as surface mobs. This causes fewer zombies to spawn in caves than there should be, and consequently causes caves to contain more monsters of other types since there is more room below the cave density cap.
Other monsters (creepers, skeletons, spiders, witches, and endermen) are not affected by this issue.
Steps to reproduce:
- Open the attached demo world
MCPE-52743.mcworld.
There is a 16 x 16 spawn floor at Y=6. The blue square you see is aligned above it. This world is configured so that no spawns can occur naturally anywhere but the spawn floor.- Place a bottom slab on the blue block in front of the bottom observer. Command blocks will replicate this across the entire blue square, hence above the spawn floor. This creates the condition necessary to spawn mobs in caves subject to the surface density cap.
- Use the button to teleport to the Testing Room.
- Use the lever to enable mob spawning. Repeating command blocks will start running that test for zombies and zombie villagers every 5 seconds. If they find any, the chat will show them.
- Wait until zombies and/or zombie villagers are found. This shows that these can spawn on blocks that qualify the mob as a surface mob.
- Disable mob spawning.
- Use the Reset button to kill all the mobs that spawned.
- Use the button to teleport back to the surface. Break the slab you placed. This creates the condition necessary to spawn mobs in caves subject to the cave density cap.
- Return to the Testing Room and enable mob spawning.
- Wait as long as you like. No zombies or zombie villagers will spawn.
Important: The ability to spawn monsters in caves subject to the surface density cap is reported as a bug in
MCPE-41273. It may be that such spawns are intended in some cases, but if not it will likely be fixed by reducing or eliminating surface monster spawns in caves. If that fix occurs before this problem, the result will be that zombies or zombie villagers will no longer spawn underground at all! Therefore, this issue needs to be fixed before, or in conjunction with,MCPE-41273.
discovered while testing
blocks
![[Mojang] Mega_Spud (Jay Wells)](../../../data/avatars/users/92696.png){kind=small}
relates to
relates to
is cloned by
![[Mod] Jarl-Penguin](../../../data/avatars/users/92849.png){kind=small}
![[Mod] OcelotOnesie](../../../data/avatars/users/43220.png){kind=small}
Zombies and zombie villagers do not spawn underground on blocks where they would be defined as cave mobs (that is, where they are subject to and contribute to the cave density cap for monsters). They do spawn in caves, but only on blocks that define them as surface mobs. This causes fewer zombies to spawn in caves than there should be, and consequently causes caves to contain more monsters of other types since there is more room below the cave density cap.
Other monsters (creepers, skeletons, spiders, witches, and endermen) are not affected by this issue.
Steps to reproduce:
- Open the attached demo world
MCPE-52743.mcworld.
There is a 16 x 16 spawn floor at Y=6. The blue square you see is aligned above it. This world is configured so that no spawns can occur naturally anywhere but the spawn floor. - Place a bottom slab on the blue block in front of the bottom observer. Command blocks will replicate this across the entire blue square, hence above the spawn floor. This creates the condition necessary to spawn mobs in caves subject to the surface density cap.
- Use the button to teleport to the Testing Room.
- Use the lever to enable mob spawning. Repeating command blocks will start running that test for zombies and zombie villagers every 5 seconds. If they find any, the chat will show them.
- Wait until zombies and/or zombie villagers are found. This shows that these can spawn on blocks that qualify the mob as a surface mob.
- Disable mob spawning.
- Use the Reset button to kill all the mobs that spawned.
- Use the button to teleport back to the surface. Break the slab you placed. This creates the condition necessary to spawn mobs in caves subject to the cave density cap.
- Return to the Testing Room and enable mob spawning.
- Wait as long as you like. No zombies or zombie villagers will spawn.
Important: The ability to spawn monsters in caves subject to the surface density cap is reported as a bug in MCPE-41273. It may be that such spawns are intended in some cases, but if not it will likely be fixed by reducing or eliminating surface monster spawns in caves. If that fix occurs before this problem, the result will be that zombies or zombie villagers will no longer spawn underground at all! Therefore, this issue needs to be fixed before, or in conjunction with, MCPE-41273.
In the vanilla behavior pack for 1.12, the spawn rules for zombies did not define them as eligible for cave spawns. Zombies were occasionally spawning underground, but only as a result of another bug, MCPE-52743. The spawn rules were fixed in 1.13.1.
Both this and MCPE-52743 are open and talking about the same issue. Excited for the fix though!
Shouldn’t this be closed as either a duplicate of MCPE-52743 or fixed?
This bug is probably also causing the issue in
MCPE-45474.If I am reading vanilla_1.15/spawn_rules/zombie.json correctly, this bug appears to be back in 1.16.
It looks like when someone added `minecraft:zombie_villager_v2` to the zombie spawn rules, they accidentally reverted the fix for this bug.
The fix was regressed in 1.16.0. It was then fixed again in 1.16.20.50 Beta. We will leave this ticket open until the fix migrates back into the general release. (No specific date can be given.)
Fixed in 1.16.20.52
AvgZing: See the comment immediately above yours and the Fix Version field.