Bedrock Edition:Half Door (Block)
Doors in Minecraft consist of two parts: the upper and lower sections. These sections are intended to be connected, but in some cases, can be separated into individual blocks, creating a half door.
Obtaining
Placement on Farmland
In Pocket Edition v0.4.0 alpha, half doors could be obtained by placing a door on top of farmland.[1]
Cactus Replacement
From Pocket Edition v0.2.0 alpha to v0.3.2 alpha, placing a door next to a cactus would result in the creation of a half door. The bug would recur in Pocket Edition v0.4.0 alpha[2] and again from Pocket Edition v0.9.0 alpha build 1 to Pocket Edition v0.10.5 alpha.[3]
Block Palette Conversion
Half doors can be obtained via block palette conversion.
Two-Block Tall Plant Replacement
From Pocket Edition v0.9.0 alpha build 1 to Pocket Edition v0.10.5 alpha, rose bushes, lilacs, and peonies could be used to create half doors by placing them underneath the block supporting the door, resulting in the flower replacing that block. Next, break the flower and place a block, leaving a one-block gap between the block and the door. Lastly, place one of those 3 flower blocks beneath the door, which results in the bottom half of the door being replaced, creating a half door. This can also be done with tallgrass and large ferns; however, they weren't obtainable in survival mode at the time, making this method exclusive to Creative mode.
Height Limit
v0.4.0 alpha
In Pocket Edition v0.4.0 alpha, placing a door one block below the height limit would create a half door.
Altitude Changes
Updating a world containing a door placed one block below the old height limit (which was 255) from Bedrock Edition beta 1.16.220.50 or Bedrock Edition beta 1.16.220.51, with the 'Caves and Cliffs' experimental setting enabled, to Bedrock Edition 1.16.220 would result in the creation of a half door.
Downgrading
Downgrading a world containing any door, except iron or oak doors, from Pocket Edition v0.13.0 alpha build 1 to any version below Pocket Edition v0.12.3 alpha, breaking either the bottom or top half of the door, then updating back to Pocket Edition v0.13.0 alpha build 1 or later, would result in the creation of a half door.