Hostile mobs are spawning on/in transparent blocks like slabs, fences, glass, etc.
I slabed off an area and put walls around hoping to prevent slime spawns in a some chunk area but they still spawn. I suspect that this might be related to MCPE-14022.
Linked Issues
is duplicated by16
MCPE-15803Mobs spawn on slabsDuplicateMCPE-16077Mobs spawn everywhereDuplicateMCPE-18018mobs are spawning on top of half slabs and railsDuplicateMCPE-18428Zombies getting stuck in oak treesDuplicateMCPE-18687Mobs in Nether spawn in incorrect locations DuplicateMCPE-20497Mobs can Spawn in transparent blocksDuplicateMCPE-20672Hostile mobs can spawn on bottom half slabs, stairs, and fencesDuplicateMCPE-22039Nether mobs spawn in unusual placesDuplicateMCPE-24715Strange mob spawning behaviorDuplicateMCPE-25053Mobs spawning on glassDuplicateMCPE-25200Hostile mobs spawning on stained glassDuplicateMCPE-26757Incorrect Mob SpawningDuplicateMCPE-27592Stained glass registering as solid block allowing mob spawning on itDuplicateMCPE-28186Mobs spawning on fence gateDuplicateMCPE-28428Mobs Spawning In Stair Blocks also and well lit areaDuplicateMCPE-28440Endermen Spawn on Stained Glass BlocksDuplicaterelates to7
MCPE-17114Mob Spawners Work in Light Level Above 12FixedMCPE-27122Mobs Spawn On Redstone ComponentsFixedMCPE-28295Endermen [and other mobs] can spawn on single layer carpetFixedMCPE-14022Covering roof of spawn chamber with bottom-half slabs severely reduces the spawn rateFixedMCPE-16643Realm - Mobs spawning on stair blocksCannot ReproduceMCPE-19735Player can place top half slab under feet while standing on bottom half slab FixedMCPE-26107Spiders spawn on leaves in Mushroom Island biome.FixedAttachments12
![[Mojang] Mega_Spud (Jay Wells)](../../../data/avatars/users/92696.png){kind=small}
![[MCPE Mod] Celesian](../../../data/avatars/users/81635.png){kind=small}
Created Issue:
Slimes are spawning on half slabs
I slabed off an area and put walls around hoping to prevent slime spawns in a some chunk area but they still spawn. I suspect that this might be related to big 14022.
Attachments1
I slabed off an area and put walls around hoping to prevent slime spawns in a some chunk area but they still spawn. I suspect that this might be related to big 14022.
I slabed off an area and put walls around hoping to prevent slime spawns in a some chunk area but they still spawn. I suspect that this might be related to
MCPE-14022.
I Think Your New To This Minecraft Concept Noob
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Slimes are spawning on half slabsHostile mobs are spawning on half slabs
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![[Bot] Arisa](../../../data/assets/gravatar/mustek2.png){kind=small}
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I cannot reproduce on v.0.16.1 on the hard difficulty testing with bottom half slabs, glass and glass with carpet. With a night vision effect for visibility. Fences to prevent mobs getting into the testing area.
On a NVIDIA Shield K1 with Android 6.0.1.
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Mob Slab Spawn World MCPE-1446.mcworld
![[Mojang] Adrian Östergård](../../../data/assets/gravatar/nighter.jpeg){kind=small}
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Hostile mobs are spawning on half slabs and other transparent blocks
Hostile mobs are spawning on half slabsand other transparent blocks
Hostile mobs are spawning onhalf slabsHostile mobs are spawning on/in transparent blocks like slabs, fences, glass, etc.
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![[MCPE Helper] Aspergerian](../../../data/avatars/users/64928.png){kind=small}
Is this still happening in 1.0.4.11?
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![[Mod] bemoty](../../../data/avatars/users/50554.png){kind=small}
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![[Mod] GoldenHelmet](../../../data/avatars/users/18951.svg){kind=small}
Thank you for your report. This issue was, however, submitted earlier as MCPE-14467. Please perform a search next time to make sure your bug hasn't already been reported. The parent issue can easily be found by searching for "mcpe unresolved spawn slab".
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-14467.
It has been linked to this report. If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-14467.
It has been linked to this report. If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki
Resolving as a duplicate of MCPE-14467.
Thank you for your report. This issue was, however, submitted earlier as MCPE-14467. Please perform a search next time to make sure your bug hasn't already been reported.
Vladimir Rizov: It would be more helpful if you could let us know exactly which report it duplicates 
This is highly related to, if not a duplicate of, MCPE-14467. Added a related link.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-14467.
It has been linked to this report. If you have additional information, please add it to that report.
If you have not, please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki
Although I did a search before creating this report, I didn't go back far enough to find MCPE-14467. This appears to be a duplicate of that report.
I have confirmed it, but I didn't see anything relevant to this in the changelog. Why do you expect it to be fixed? Is there another source for fixes I can cite when mentioning this was fixed on the wiki?
BTW, this fix may also have fixed MCPE-25514 and MCPE-14467. They weren't identified as dupes, but I think they all had the same root cause.
Thank you for your report!
However, this issue is a Duplicate of MCPE-14467.
If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
Thank you for your report!
However, this issue is a Duplicate of MCPE-14467.
If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
Thank you for your report!
However, this issue is a Duplicate of MCPE-14467.
If you have additional information, please add it to that report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-14467.
Your additional information and observations are very useful, so if you can add them to the comments section of the parent issue it would be appreciated.
If you have not, you might like to make use of the search feature before making a new ticket, as it's likely that the issue has been reported already.
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This may or may not be a duplicate of MCPE-14467. All the specific cases you mentioned are covered by 14467, but if you see any monsters spawning at night on regular solid blocks where the light level is 8 or higher, this is a different issue. Please clarify.
Larry Jones: The other ticket is marked resolved because it doesn't mention anything about light levels, only transparent/non-solid blocks. That is a different issue which overlaps this one, and that part of it has been resolved. My request for clarification was to get a discriminating test case that establishes that this part of it remains unresolved, and you have provided that by confirming that creepers still spawn on solid blocks at higher light levels. Thank you for the confirmation.
Mods: This does not appear to be a duplicate of MCPE-14467.
Relates to MCPE-14467, but has a broader scope.
Duplicate of MCPE-14467, please use the search function before making a report.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-14467.
It has been linked to this report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Feedback – 📖 Game Wiki
Top-half slabs don't prevent any mobs from spawning. Only bottom-half ones do.
See http://minecraft.gamepedia.com/Spawn#Spawn_conditions
I know that top slabs don't prevent spawns those are all bottom slabs and the slimes still spawn. Please reopen.
Tested on bottom slabs and confirmed.
I think this bug might be more far reaching than just just Slimes.
I covered a fenced off 22x22 area of bottom-half slabs where I had seen a slime spawn on a flat world.
I couldn't get a slime to spawn (possibly needed more time!) but other mobs were spawning on the half slabs as pictured:
Because of 14022 I suspected that this might be part of a more general bounds checking bug which would affect all mobs, but I had only seen the slimes spawn on the bottom slabs.
Reopened.
Happens for me too, annoying
Please respond and add the current version if you can reproduce this issue.
It still effects 15.4
Strangely enough, I cannot see any non-slime hostile mobs spawning on top of bottom-half slabs in 0.15.4.
I made an 8x8 spawn pad and stood 24 blocks away from it in a flat world. Mobs did not spawn at all no matter how long I waited for. I haven't tested for slimes yet.
They do spawn, so i had to change to bottom half-slabs to a leaves, or put carpets on it, whcih looks a bit awkward (Bottom half-slab with a carpet on it) but at least it does prevents the spawn.
I posted the issue i believe, with screenshots
I have a railroad track built 100% on half slabs 4 blocks below the build limit. All blocks within 1000 spaces horizontally and 60 vertically are half slabs. Hostile mobs spawn on it. Also, I have a roof that is 100% half slabs and my nearby golem farm spawns golems on it. Not sure if golems are considered hostile or passive.
I tested in Win10 0.15.7: built 4 darkened spawn rooms with floors of half-slabs, glass, half-slabs+carpet, and glass+carpet. The only one to spawn anything was the room with half-slab floors, several hostile mobs spawned pretty quickly.
This bug has been reported to our internal bug tracker for further testing and a fix. It is scheduled to be fixed in one of the future updates (no specific date can be provided).
This is a bulk resolve of issues that haven't been updated to 0.16.0+ yet. Please comment below (To open the ticket) and update your affected versions. If you cannot reproduce the bug, please write in the comments so we can resolve it as "Cannot Reproduce". Thank You!
I cannot reproduce this bug on v.0.16.1 on the hard difficulty testing with bottom half slabs, glass and glass with carpet. With a night vision effect for visibility. Fences to prevent mobs getting into the testing area.
On a NVIDIA Shield K1 with Android 6.0.1.
See image "20161118" for the testing area for this bug
Confirmed to affect 0.17.0.2
Tested on Samsung TabPro SM-T520 on Android 4.4.2
If you are refering to upside down half slabs (where the slab makes up the top half of the block area rather than the bottom half), this is normal. Mobs can spawn on these.
Version 1.0 , mobs still spawn on bottom half slabs here is a video to prove it
https://youtu.be/MYU1bt0r_DY
I can get mobs to spawn on bottom-half slabs when they are on another block; it's as if they ignore the half slab entirely. They also spawn inside glass that is on another solid block, again, ignoring the glass.
Attached test world. Notice the glass area too.
They can't completely ignore bottom half slabs because they prevent the mods from spawning beneath the block they are on as can be seen from bug 14022.
Confirmed to affect 1.0.4 on Win 10 64 bit. Not only slimes, but zombies, skeletons, spiders and creepers. Haven't seen witches yet but assume affects them too.
it does
Attached another test world: "Mobs spawning on slabs.mcworld"
On 1.0.7 mobs don't spawn on/inside the following blocks:
And they spawn on/inside the following blocks:
Reuploaded "Mobs spawning on slabs.mcworld" to fix a mistake in the floor selection system.
Re-uploaded "Mobs spawning on slabs.mcworld" so you can choose the floor type from 16 different blocks.
It's happening on iOS 10.2.1 as well.
Still affects 1.2.0.18 according to various reports, including
MCPE-25053Affects 1.2.0.22 and 1.2.0.25.
That is annoying, even after an update of 1.2.0.25, still a creeper spawn on my stair only roof and a spider spawn on tree leafs. I have to force myself to play peaceful mode.
I guess there's no need to say that it is still happening in 1.1.5 since it is happening in 1.2, but I will anyway. I spent hours building a large area in the nether with bottom half slabs in my "safe" area and as the roof for a wither skeleton farm ala tango's design only to find mobs spawning in both the "safe" area and on the roof. I was already annoyed because blazes could see me over the walls that only wither skeletons were supposed to see me over, but the spawning on bottom half slabs is a huge issue for the farm. All of this is on top of discovering that fighting the wither absolutely destroys the game with lag which makes the entire farm a wasted effort anyway.
Although the changelog says nothing about fixing it, this doesn't seem to be happening any more for me since upgrading to 1.2.0.31/build 9. Yay!
mobs still spawn on glass block, im currently in beta 1.2 build 9
Still happening in 1.2 official release
Windows 10
The problem returned in 1.2.1 for me.
Can confirm mobs are still spawning on glass, leaves, etc. I'm on a realm server on xbox
Still happening in new update 1.2.2
Update 1.2.2 spawns on at least glass, carpets and stairs!
Confirm still spawning on glass and leaves in 1.2.3.6.
Mobs are spawning on fence gates...
This issue is fixed in 1.2.5.12!!!!!!!!!!!
Tested in creative and survival.
Mobs don't spawn on glass, slabs, stairs, fences, fence gates.
Only spiders spawn on leaf blocks.
The issues with spawning appear to be fixed in 1.2.5.12.
the remaining issue with spiders spawning on leaves is being tracked at
MCPE-26107I've seen monsters spawn right next to torches and glowstone, so light levels should be checked too.
I don't agree with 'fixed.' They are spawning in any light levels..
Joe Smith: A helper noted that your issue
MCPE-28426is a duplicate of this one because all the specific cases you listed could be the result of this issue. However, your assumption that mobs were spawning at too-high light levels would not be covered, so we need a test case that demonstrates that. I updatedMCPE-28416to request a clarification. Please answer there.This issue is specifically about spawning on transparent or non-solid blocks, and as far as we know that problem has been fixed, so this ticket will remain closed unless a counterexample is reported.
I don't think this issue is fixed. Endermen still spawn on the main island of the End (where the dragon spawns), even if the ENTIRE surface is covered with water. They spawn on glass blocks and on top of the bedrock regardless of light level. They do not spawn on bottom-placed slabs. I have reported it.
This fix has broken parity with Java. Before, mobs could and should have spawned on top slabs as it was a solid flush spawning surface for them. Now, mobs no longer spawn on top slabs. A proper fix would be mobs not spawning on bottom slabs, but spawning on top slabs.
Mobs spawning on glass again in 1.2.13.6
Reopened ticket - mobs were spawning in on glass. (They were spawning in on top-half slabs though, which is better than previously reported behaviour.)
Mobs still spawning on slabs, stairs, glass, fence gates, etc.
Windows 10 beta 1.2.13.8
This is easily reproduced by opening a world in creative and using commands to fill in space with transparent blocks.
Issue still persists in 1.2.13.10
Carpets do not prevent spawns as stated in 1.2.13 changelog
Android 1.2.13.60
I'm playing the console edition (Xbox 360). I know it's on or after TU69-Aquatic Update; I believe it is TU73, because I do have the trial version of the Nightmare Before Christmas Texture Pack.
I am playing on Adventure Mode / Hard Difficulty (world created in Survival).
My seed is -2878103199665976685, and I found a zombie spawner at X 296 - Y 57 - Z 78.
I placed half-slabs on the ground to limit the eligible spawn locations (I left open 3 in the 3 corners and 2 on the 2 far walls for mob spawning) and placed blocks above those spaces (with a 2-tall gap) to keep the spawned zombies stuck in place for carrot/potato/equipment farming. When I removed the torches, the zombies began spawning on the upside-down (lower-half) slabs.
I dug up the half-slabs and replaced the layer of cobblestone beneath them with glass blocks. The mobs spawned on the glass.
I crafted shears, got some leaves blocks from a nearby spruce tree and replaced the glass with leaves. The mobs spawned on the leaves. (I saved after the glass trial, but I did not save after the leaves trial, so the picture shows glass.)
I am not seeing anything in the change logs to suggest they are now supposed to be spawning on transparent blocks. Please re-open this Issue and investigate or create a new Issue and reply to this with the new issue number (so I know where to find it).
Thank you for your help,
Tony
PS - I cannot confirm or deny if this is affecting any other versions or updates.
@Anthony Yarbrough Issues with the Legacy console editions need to be logged in the console edition (project key MCCE) section of the bug tracker: https://bugs.mojang.com/projects/MCCE/summary, as this section is for issues related to the Bedrock codebase (project key MCPE).
This issue has re appeared in the latest beta. 1.14.0.2
I've got a giant hole with nothing but glasts and bedrock blocks on the bottom. At night, the hostile mobs still spawn.. I've attached a screen cap taken during the day, but you can see the slimes down there. The second is at night. The mobs are not easy to see. I have circled a few.
Update... Issue persists in beta 1.14.0.50.
Mobs are also spawning on leaf blocks. (Dark oak and spruce for sure. Haven't tested others)
@Brad Canney, you should open a separate issue for mobs spawning on bedrock, since bedrock is not a transparent block.
Oh sorry. I should have included an update there too. I've removed the glass for 1/4 of my hole and The mobs don't spawn there. They most be spawning on the glass blocks
@Brad Canney The issue with leaves and glass is being tracked at a new issue:
MCPE-54241.Current issues with spawning on leaves and glass are being tracked as
MCPE-54241. You may want to upvote and/or watch that ticket instead.