The bug
When you place a block that is used to fall (sand, gravel, or anvil) up to a dual grass block or any new plant of two blocks height and break the grass the block just gets stuck when it was supposed to fall.
Code analysis
Code analysis by @unknown can be found in this comment.
Related issues
is duplicated by
MC-30349
Anvil and sands floats when double tall grass is destroyed
MC-37924
Sunflower can make gravel float when broken
MC-40491
When placing double tall grass, setting the top block on fire, then destroying it, leaves the light and sound of the fire block.
MC-50159
Floating sand still in 1.8 snapshots
MC-51665
Two High Plant Bug
MC-52906
Gravel can be placed on tallgrass+doesn't fall
MC-55662
Gravel will float if placed on top of Double Tallgrass then bottom block of Double Tallgrass is destroyed.
MC-59544
None falling sand when placed on double grass
MC-79904
2-block tall flowers can be used to make sand float
MC-85904
Creating double tall grass with a carpet.
MC-98378
Floating Sand
MC-101525
The sand won‘t fall
MC-108569
floating sand
MC-127697
Gravity based blocks will float if the tall grass it rests on is broken from the bottom layer
relates to
Attachments
Comments
migrated
Confirmed.
Affects 14w04a
Appears to only affect the bottom block since 14w06b.
Confirmed for 14w11b (lower part)
Confirmed for 14w26c
Confirmed for 1.8pre2
Confirmed in 1.8.
Confirmed for 1.8.3
Confirmed affecting 1.8.3 here too (used red sand on peony)
Sorry if I posted this here. Is there a way that I can edit the post so I can add my MC version affected with that bug or I will just needed to comment "Confirmed for ..*" and a mod will rescue and put it into the "Affects Versions" tab in the post?
No, you are correct. Only the reporter of an issue and mods can edit it, for security reasons.
Confirmed for 15w46a
Floating sand can't be done using /setblock command. and only can be done using this method. Weird. :[
Confirmed for Minecraft Release 1.9
marcono1234
Please link to this comment in the description
The following is based on a decompiled version of Minecraft 1.9 using MCP 9.24 beta.
It looks like the reason for this are missing block updates. The problem is that currently the class net.minecraft.block.BlockDoublePlant overrides the method net.minecraft.block.Block.onBlockHarvested(World, BlockPos, IBlockState, EntityPlayer), which is called before the block is set to air. Because of this it cannot replace the other plant part with an update. If it would do that the update would cause the harvested part to be detected as incomplete because it was not removed yet.
To solve this the class should probably override the method net.minecraft.block.Block.onBlockDestroyedByPlayer(World, BlockPos, IBlockState) instead which is called after the block was replaced. Then block updates can be applied without any side effects (hopefully).
Have a look at the method net.minecraft.server.management.PlayerInteractionManager.removeBlock(BlockPos) to see the order.
confirmed for 1.10.2
Please don't fix this bug 😞
pokechu22
Looks like it was 1.13-pre3 :/