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  1. Minecraft: Java Edition
  2. MC-69876

Pistons at Y=1 do not push downwards / at Y=254 do not push upwards


    • Icon: Bug Bug
    • Resolution: Fixed
    • 1.16.2 Pre-release 2
    • Minecraft 1.8-pre3, Minecraft 1.8, Minecraft 1.8.7, Minecraft 15w36d, Minecraft 16w35a, Minecraft 1.11, Minecraft 1.11.2, Minecraft 17w17b, Minecraft 1.13.1, Minecraft 1.13.2, Minecraft 18w45a, Minecraft 18w46a, Minecraft 18w48a, Minecraft 18w48b, Minecraft 18w49a, Minecraft 18w50a, Minecraft 19w02a, Minecraft 19w03a, Minecraft 19w03b, Minecraft 19w03c, 20w18a, 20w21a, 1.16 Pre-release 2, 1.16 Pre-release 3, 1.16 Pre-release 5, 1.16.1, 20w28a, 20w29a, 20w30a, 1.16.2 Pre-release 1
    • None
    • Confirmed
    • (Unassigned)

      The bug

      A piston placed at Y=1 will not push downwards. This also happens at Y=254 with an upward facing piston.

      Code analysis

      Based on 1.11 decompiled using MCP 9.35 rc1

      The method net.minecraft.block.BlockPistonBase.canPush(IBlockState, World, BlockPos, EnumFacing, boolean) allows piston movement only if the piston is not facing downwards or the potential block to move is not at y 0. It should allow piston movement as well if the block is air or has EnumPushReaction.DESTROY as push reaction.

            xilefian [Mojang] Felix Jones
            Awesoman3000 Connor Steppie
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