Buttons and non-full blocks do not prevent spiders from spawning

Just to be clear, spiders have never required a 3x3 area to spawn in Bedrock Edition. They only require a 2x2 area because spawning occurs at the north-west corner of blocks.

Have you tested with a button in every 2x2 area? What other blocks have you tested besides buttons?

This bug seems to “break” creeper farm. Don’t know if replacing trap doors in the holes with buttons will help. 

This bug seems to “break” creeper farm. Don’t know if replacing trap doors in the holes with buttons will help. 

My creeper farm has also stopped blocking spider spawns, this is the configuration of the buttons. Torches are temporary so you can see the buttons. Usually it is pitch black in here. 🙂

@GoldenHelmet - My bad on the 3x3, spiders shouldn't be allowed to spawn on this farm though. Here is an image of the same design I have 

Every other row has holes every 2nd block, above every bare full block (without a button) has a trapdoor above it. Spiders are spawning on every level of the farm. It was double checked to be consistent for every level and not missing any buttons. It was working efficiently prior to 1.20.30 update today.

I switched all of the buttons on 4 of my levels to Moss Carpet and noticed a few spiders on each floor. I can try other blocks tonight but I hear that Glass panes do not work, carpets do not work, iron bars do work so far, Fence posts seem to fix it but get other mobs in the farm stuck. 

@GoldenHelmet - My bad on the 3x3, spiders shouldn't be allowed to spawn on this farm though. Here is an image of the same design I have 

Every other row has holes every 2nd block, above every bare full block (without a button) has a trapdoor above it. Spiders are spawning on every level of the farm. It was double checked to be consistent for every level and not missing any buttons. It was working efficiently prior to 1.20.30 update today.

I switched all of the buttons on 4 of my levels to Moss Carpet and noticed a few spiders on each floor. I can try other blocks tonight but I hear that Glass panes do not work, carpets do not work, iron bars do work so far, Fence posts seem to fix it but get other mobs in the farm stuck. 

Moss carpet may be intended to be spawnable since it is spawnable in Java (MCPE-155420 may actually be fixed). I believe glass panes and iron bars were always too small to block spiders, but fence post have always worked.

There are some farm designs that use fence posts or connected wall blocks, or allow spiders to spawn and flush them efficiently, which you could use as a workaround.

@GoldenHelmet Moss carpet in Bedrock are treated like wool carpet, can confirm from my SMP base on the previous season that ended 9/1/23.

As for the spiders spawning where they shouldn't because something broke with buttons I present the following screenshots. Ghost overlay is courtesy of MaddHatter and Bud's Technical Resource pack.

@GoldenHelmet Moss carpet in Bedrock are treated like wool carpet, can confirm from my SMP base on the previous season that ended 9/1/23.

As for the spiders spawning where they shouldn't because something broke with buttons I present the following screenshots. Ghost overlay is courtesy of MaddHatter and Bud's Technical Resource pack.

" Reed Cartwright added a comment - 20/Apr/22 7:00 PM - edited

I figured out what changed in 1.18.30 that broke creeper farms.

Code Analysis

When spiders (and most mobs) spawn, the game will cancel the spawning attempt if the mob collides with any block that has an AABB (axis-aligned bounding box). The function used for this is the virtual function BlockLegacy::getAABB() or its overrides. A refactoring occurred between 1.17 and 1.18 that added a boolean parameter to this function. I'll call it param_5. When param_5 is set to false, many blocks return an empty AABB. This is likely used to distinguish different types of AABBs, such as collision boxes or hit boxes. Notably param_5 is set to false when the game checks if a mob collides with any block.

In 1.18.30, ButtonBlock::getAABB() has been added to the game. (Buttons used BlockLegacy::getAABB() in earlier versions.) The dev who wrote this function included logic that returns an empty AABB if param_5 is false. This returns an empty bounding box during mob spawning, causing buttons to stop blocking spider spawns. This isn't a minor inconvenience. Even a small creeper farm can have thousands of buttons that would need to be replaced by an alternative block (if one even exists).

The Fix

Remove the logic in ButtonBlock::getAABB() that returns an empty bounding box if param_5 is false. ButtonBlock::getAABB() should always return an accurate bounding box regardless of the value of param_5. Given how quickly changes to pathfinding on coral fans was fixed, I hope that this bug can be quickly fixed as well."

I have a feeling this might be the fix/what broke it this time again.

" Reed Cartwright added a comment - 20/Apr/22 7:00 PM - edited

I figured out what changed in 1.18.30 that broke creeper farms.

Code Analysis

When spiders (and most mobs) spawn, the game will cancel the spawning attempt if the mob collides with any block that has an AABB (axis-aligned bounding box). The function used for this is the virtual function BlockLegacy::getAABB() or its overrides. A refactoring occurred between 1.17 and 1.18 that added a boolean parameter to this function. I'll call it param_5. When param_5 is set to false, many blocks return an empty AABB. This is likely used to distinguish different types of AABBs, such as collision boxes or hit boxes. Notably param_5 is set to false when the game checks if a mob collides with any block.

In 1.18.30, ButtonBlock::getAABB() has been added to the game. (Buttons used BlockLegacy::getAABB() in earlier versions.) The dev who wrote this function included logic that returns an empty AABB if param_5 is false. This returns an empty bounding box during mob spawning, causing buttons to stop blocking spider spawns. This isn't a minor inconvenience. Even a small creeper farm can have thousands of buttons that would need to be replaced by an alternative block (if one even exists).

The Fix

Remove the logic in ButtonBlock::getAABB() that returns an empty bounding box if param_5 is false. ButtonBlock::getAABB() should always return an accurate bounding box regardless of the value of param_5. Given how quickly changes to pathfinding on coral fans was fixed, I hope that this bug can be quickly fixed as well."

I have a feeling this might be the fix/what broke it this time again.

My creeper farm (which uses buttons) was working perfectly before 1.20.30. After updating I decided to afk at the farm for a few hours. When I came back it had only produced two stacks of gunpowder (normally its always been 10+ stacks) and to farm was FULL of spiders no mobs were spawning anywhere near the farm as the spiders couldn't fall into it and instead clogged it up and completely took over the mob cap. Does anyone know an alternative block I can replace the buttons with without preventing the creepers from walking through the trapdoors?

My creeper farm (which uses buttons) was working perfectly before 1.20.30. After updating I decided to afk at the farm for a few hours. When I came back it had only produced two stacks of gunpowder (normally its always been 10+ stacks) and to farm was FULL of spiders no mobs were spawning anywhere near the farm as the spiders couldn't fall into it and instead clogged it up and completely took over the mob cap. Does anyone know an alternative block I can replace the buttons with without preventing the creepers from walking through the trapdoors?

My creeper farm is also spawning Spiders now

My creeper farm is also spawning Spiders now

All of my creeper farms are full of spiders. And the latest snapshot did not include a fix for this issue 

All of my creeper farms are full of spiders. And the latest snapshot did not include a fix for this issue 

Affects versions 1.20.31.1; 1.20.40.22

Affects versions 1.20.31.1; 1.20.40.22

I don't understand how this bug returned and is not elevated to a hotfix scenario. The spiders clearly spawn where they should not when buttons are placed in a general or creeper farm rendering all of said XP farms for Bedrock...useless.

I don't understand how this bug returned and is not elevated to a hotfix scenario. The spiders clearly spawn where they should not when buttons are placed in a general or creeper farm rendering all of said XP farms for Bedrock...useless.

Still a problem!

Still a problem!

Still not working. Hope this gets fixed soon. I just built a 6 layer creeper farm only to watch it fill up with spiders. 

Still not working. Hope this gets fixed soon. I just built a 6 layer creeper farm only to watch it fill up with spiders. 

Are there any modifications that can be made to prevent this?

Are there any modifications that can be made to prevent this?