[MC-90523] falling_block entity floating on fences/walls

What I expected to happen was...: -
the block to render properly on the fence.

What actually happened was...:
it glitched out on the fence and could not mine it until breaking the fence underneath, sometimes it dropped the block as an item, sometimes it rendered the block there

Steps to Reproduce:
1. Put a fence down a few blocks below where you're going to drop the block which becomes a falling entity
2. Let it drop
3. Enjoy

Code analysis by @unknown in this comment

Code analysis and comment by @unknown from MC-99860

Since 15w38b, falling blocks will not stop falling if the AAAB below them is greater than one block tall, as a result of:

if (BlockFalling.j(this.world.getType(new BlockPosition(this.locX, this.locY - 0.009999999776482582D, this.locZ)))) {
                        this.onGround = false;
                        return;
                    }

Linked issues

is duplicated by 41

MC-4918 Minecraft crashes after destroying snow. Resolved

MC-90562 Falling Sand vs. Fence Posts Resolved

MC-91670 Floating Sand Entity on Any Fences/Cobblestone Walls Resolved

MC-92778 Up sand Cobblestone wall Resolved

MC-94256 Sand glitches on top of fence posts remaining in falling state Resolved

36 more links

relates to 4

MC-139493 Falling blocks float on snow layers Resolved

MC-143894 Falling blocks can land on blocks they're not supposed to Open

MC-89000 Falling Sand doesn't get killed if falling on edge of block Resolved

MC-144263 Anvils glitch out and make noise when dropped on shulker Resolved

Attachments

Comments 55

[Bot] Arisa 2015-10-13T04:44:00Z

Please do not mark unreleased versions as affected.
You don't have access to them yet.

--- I am a robot. This action was performed automatically.

kumasasa 2015-10-30T06:44:35Z

Maybe related to the new entity collision check. The fences and cobblestone wall have a collision box of 1.5 blocks height.

[Mod]Les3awe 2015-10-30T10:19:59Z

Confirmed.
Also affect the Red Sand.

Screenshot

[Mod]Les3awe 2015-11-01T16:48:17Z

Confirmed for 15w44b

[Mod]Les3awe 2015-11-07T04:10:35Z

Also affect the Anvil.

Screenshot

45 more comments

[Mod]Les3awe 2015-11-12T14:43:04Z

Confirmed for 15w46a

Irbis 2015-11-18T18:00:40Z

15w47a

[Mod]Les3awe 2015-11-28T05:03:31Z

Confirmed for 15w47c

marcono1234 2015-12-11T14:46:09Z

Confirmed for

15w50a This however did not happen in 1.8.9

The problem seems to be that the OnGround tag is not correctly set for FallingSand. Only if it is true it will land, however it is false.

This does not only affect fences but also FallingSand that is partwise on a block, power for example a command block containing this command:

/summon FallingSand ~0.8 ~1 ~ {Time:1b}

Irbis 2015-12-17T18:45:34Z

15w51b

[Mod]Les3awe 2016-01-24T17:54:52Z

Confirmed for 16w03a

[Mod]Les3awe 2016-01-24T18:05:44Z

Can also be used fence gate to reproduce.

[Mod] Neko 2016-01-28T19:34:51Z

Confirmed for 16w04a

[Mod] Neko 2016-02-03T19:31:23Z

Confirmed for 16w05a

[Mod] Neko 2016-02-04T19:34:42Z

Confirmed for 16w05b

[Mod] Neko 2016-02-10T19:55:37Z

Confirmed for 16w06a

Jeremy 2016-02-11T00:01:45Z

This also allows the player to pass through the block as the sand is still in entity form. This allows players to create '1 block' gaps in survival.

[Mod] Neko 2016-02-15T18:37:07Z

Confirmed for 16w07a

[Mod] Neko 2016-02-16T19:14:14Z

Confirmed for 16w07b

[Mod] Neko 2016-02-17T20:29:06Z

Confirmed for 1.9 Pre-Release 1

[Mod] Neko 2016-02-18T20:49:51Z

Confirmed for 1.9 Pre-Release 2

[Mod] Neko 2016-02-24T19:27:09Z

Confirmed for 1.9 Pre-Release 3

Roy Sajima 2016-02-26T16:09:54Z

Confirmed for 1.9 Pre-Release 4

marcono1234 2016-03-08T17:17:59Z

Please link to this comment in the description

The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.

The reason why this happens is because the net.minecraft.entity.item.EntityFallingBlock.onUpdate() method tests if the falling sand entity is on ground if the block it is in is either fire, air, water or lava (method net.minecraft.block.BlockFalling.func_185759_i(IBlockState)). If this is the case it returns, else it tries to place the block. Currently I cannot think of any situation in which the falling sand is on ground but should not land or drop as an item.

[Mod] Neko 2016-03-09T19:27:02Z

Confirmed for 1.9.1 Pre-Release 1

[Mod]Les3awe 2016-03-10T17:25:08Z

Also affect Dragon egg.

[Mod]Les3awe 2016-03-10T17:25:35Z

Confirmed for 1.9.1-pre2

[Mod] Neko 2016-03-11T19:24:36Z

Confirmed for 1.9.1 Pre-Release 3

[Mod] Neko 2016-03-30T18:37:41Z

Confirmed for 1.9.1 and 1.9.2

[Mod] Neko 2016-04-07T18:24:31Z

Confirmed for 16w14a

[Mod] Neko 2016-04-11T18:41:27Z

Confirmed for 16w15a

[Mod] Neko 2016-04-13T18:53:16Z

Confirmed for 16w15b

[Mod] Neko 2016-04-22T02:03:55Z

Confirmed for 1.9.3 Pre-Release 1

[Mod] Neko 2016-04-27T23:41:06Z

Confirmed for 1.9.3 Pre-Release 2

[Mod] Neko 2016-05-03T20:18:31Z

Confirmed for 1.9.3 Pre-Release 3

[Mod] Neko 2016-05-21T20:38:41Z

Confirmed for 1.9.3, 1.9.4 and 16w20a

[Mod] Neko 2016-05-26T18:40:50Z

Confirmed for 16w21a and 16w21b

[Mod] Neko 2016-06-02T19:05:41Z

Confirmed for 1.10-pre1

[Mod] Neko 2016-06-07T19:27:41Z

Confirmed for 1.10-pre2

Zachary Cook 2016-06-08T21:24:53Z

Confirmed for 1.10

Purpur 2016-08-11T20:11:59Z

Is this ever going to be fixed? It just needs to drop as an item. It never changes back to block form because the walls and fences are higher than one block.

Plagiatus 2016-09-08T07:48:08Z

The half falling/suspended FallingSand entity in this state also deletes arrows that hit it from above.

[Mod]Les3awe 2017-02-09T01:40:57Z

Also affect the concrete powder.

bemoty 2017-07-11T00:40:07Z

Still in Minecraft 1.12.

Icarus with Parachute 2018-04-20T21:41:10Z

Observed in 18w16a.

carly strogonoff 2018-06-16T22:49:58Z

I think this "bug" is fine, it's almost impossible to stumble across randomly and doesn't impact the game negatively at all. It also has some cool uses, like using redstone to change a pixel's color on a map, as floating sand doesn't render on maps but fences and non-floating sand do.

komaramune 2018-06-17T00:23:38Z

I think this "bug" is very serious.
The falling_block that got into this state is very difficult to remove.
This bug often occurs when falling_block is used with a command.

md_5 2018-06-17T00:30:58Z

Plus you can create infinite of them = server lag.
It definitely is a bug that needs to be fixed (an exploit in my opinion even).

Egor Hans 2018-06-17T15:14:59Z

I consider this a "useful" bug. It allows for some really neat aesthetic shenanigans, as well as really cool hidden passages. I vote for leaving this bug in (and preventing it from causing lag instead if possible).

Siravid Chit-Arkhah 2018-07-17T00:06:27Z

I recently opened my world with falling block entities in 1.13 prerelease and they all converted to the same block. This may be that 1.13 redid the blocks and since it is a falling block, it converts to default.

Hraefin 2018-07-19T03:24:09Z

Can we please get a final ruling on this? At one point it was stated this was works as intended . Taking this out of the game will break things and not add anything to the game... Many thing can lag the game if you play foolishly.

komaramune 2019-02-06T18:00:20Z

I am very glad that this bug was fixed.
Don't be so sad, It is just that returned to the original state.
Finally I came to be able to summon falling_block without worrying that falling_block will continue to increase in the world.

Reporter Site 2021-02-05T20:21:20Z

What about old consoles then?

for bedrock it gets destroyed if it land on fence

for old consoles its still a valid bug

marcono1234 2021-02-05T22:01:18Z

@@unknown, this report is only for the MC project which is Minecraft: Java Edition.
Additionally as far as I know the old console versions do not receive any updates anymore (and bugs for them are not tracked here anymore either, see description of MCCE project).

Reporter Site 2021-02-07T00:12:49Z

Welp i guess consoles are discontinued

the falling sand was fixed on 1.14 but for bedrock it gets destroyed when falls on the fence