Java Edition:Half Double Chest
Two generation bugs would not properly update chests and could create a half double chest not connected to another half. During 1.13-pre6, a bug occurred when double chests were generated over a chunk boundary that would not properly connect them. From 17w47a to 21w20a (a 1.17 snapshot), water and lava pools would not update the half of a double chest when it destroyed the other half. Additionally, update suppression, chunk savestating, and chunk regeneration can also produce some configurations.
Obtaining
Chests Across Chunk Borders
In 1.13-pre6, chests that generated across chunk boundaries would not be properly connected.[1] Half of the double chest becomes a double chest, and the other half remains a single chest. These chests will always have a single chest bordering the half of the double chest.
This bug only occurs in woodland mansions and possibly in specific dungeons[test], since they are the only structures that generate double chests in this version. The "large storage room" of the woodland mansion has 7 chances for a chunk boundary to split a double chest, and the "small storage room" has two chances. Due to a separate bug, only 50% of rooms will properly place double chests.[2]
Known seeds and coordinates:
-9081407751656513996 : 5344 65 -10922 1224178737854011034 : 18443 68 -68436 105560318 : -9839 73 -7108
Note that all known seeds are from the woodland mansion "large storage room". None are currently known utilizing the "small storage room" or a dungeon.
Liquid Pool
From 17w47a (a 1.13 snapshot) to 21w20a (a 1.17 snapshot), liquid pools would not update half of a double chest when destroying the other half.[3] These chests will always have cave air bordering the half of the double chest. This can only occur if a liquid pocket intersects a woodland mansion.
Known seeds and coordinates:
-8319794722483450039 : -3453 66 4051 (tested in 1.15 - 21w20a)
Chunk Savestating and Regeneration
From 17w47a (a 1.13 snapshot) to 25w42a (present), chunk savestating and regeneration can be used to split double chests across chunk borders.
For chunk savestating, place the block to be the other "half" of the double chest on the border of one chunk and save it to disk. Savestate that chunk, break the block, and place a chest where that block was and another across a chunk border to create a double chest. Reload the chunk. Upon reloading, the block saved before the savestate will become the other half of the double chest.
For chunk regeneration, place a double chest across a chunk border. Regenerate one of the chunks. Whatever block that is placed from world generation into the location of the half of the chest in the chunk that was regenerated will become the other half of the double chest.
Update Suppression
Update suppressing the placement of a chest will prevent the placed chest from updating its state when connecting to a neighboring chest. The neighboring chest becomes a double chest, while the placed chest remains a single chest.
Updating
From 17w47a (a 1.13 snapshot) to 19w38b (a 1.15 snapshot), a type "right" half double chest renders the full double chest, and a type "left" appears invisible. From 19w39a to 19w41a (1.15 snapshots) causes the type "left" chest to no longer appear invisible and to render the full double chest. From 19w42a (a 1.15 snapshot) to 25w42a (present), neither render the full double chest, instead only rendering the half that they represent. Blocks can be placed and broken adjacent to a half double chest, the only exception being chests, which update the half double chest and convert it to a single chest.[test] Half double chests can be opened and items can be stored inside.
Gallery
A type "right" half double chest during 1.13-pre6 - 19w41a
A type "left" half double chest during 1.13-pre6 - 19w38b
A type "right" half double chest from 19w42a - 25w42a (present)
A type "left" half double chest from 19w42a - 25w42a (present)
A half double chest generated from a woodland mansion intersecting a liquid pocket
References