The bug
cave_air is meant to be used during world generation only and should afterwards be replaced by normal air, however for most features this is not the case, leaving cave_air behind.
Linked issues
is duplicated by
MC-133549
Underground structures generate using non-air blocks
MC-133980
When a cave is created, it is filled with blocks that are not transparent air blocks
MC-135705
Fill Command not replacing correctly in specific instance
MC-136336
Air in Ravines/Caves not actually air
MC-144924
Air does not generate in caves
MC-145573
Caves create empty blocks instead of air
MC-162653
/fill to replace air not working in naturally generated caves/structures
MC-165084
Fill command does not fill computer generated AIR below-ground (caves)
MC-172955
NOT A BUG, PLEASE CLOSE Minecraft isn't detecting air in lower levels
MC-176728
Cave air in nether caves
MC-190996
fill command bug
MC-198369
/fill [x1 y1 z1] [x2 y2 z2] stone replace air Returning "No Blocks Filled"
MC-202765
Naturally Generated Air Blocks not Filled with /fill replace
MC-231709
Generated air doesn't update properly when replaced via fill
MC-279124
Some Structures generate Vacuums
Comments
migrated
migrated
Affects 18w22c
migrated
Affects 1.13-pre4
migrated
Affects 1.13-pre6
migrated
Affects 1.13-pre8
migrated
Affects 18w31a, see also MC-125138.
migrated
Still in 18w50a.
migrated
Why is this an issue ? cave_air acts exactly as normal air
Yellow01
Duplicates of this bug report claim that /fill and /setblock cannot replace air in caves. cave_air and air are technically different block ids.
gaspoweredpick
Confirmed for 19w09a (by using the fill command in caves)
migrated
Still an issue in 20w10a
migrated
Could a "minecraft:airs" block tag be added to contain air, cave_air, and void_air? That would easily allow commands to test for air blocks while still allowing a distinction to be made when trying to detect where a player is.
migrated
Why is this won't fix? this issue breaks a lot of commands and a simple fix would be to add an #air block tag
migrated
This is actually useful. It's a very easy way to define caves from everything else. Of all things this shouldn't be considered a bug in the first place.
tryashtar
Checking for cave air to determine whether an area is underground isn't very reliable, since it turns back to regular air whenever a block is mined
muzikbike
Should this be reopened given changes to cave generation in 1.17 and 1.18?
migrated
I also don't see the valid reasoning behind this. I would use it in world generation only anyways. It's an easy way to check against air, that is not part of the surface. Now that its gone, I have to apply various new checks in its place, which unnecessarily bloats code.
Uriel Salischiker
Still an issue in 18w20a