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  1. Minecraft (Bedrock codebase)
  2. MCPE-30805

Pistons moving while extending can delete blocks and/or move blocks sideways



    • Bug
    • Resolution: Cannot Reproduce
    • None
    • None
    • Confirmed
    • Windows
    • 97228 / 85971


      I created a machine for the sole purpose for testing if/when pistons bug out and how they do so. Two weeks ago I posted two results, the first I added to MCPE-16314, which I deemed most relevant to the issue, and is still marked as "Resolved: Fixed". The second I added to MCPE-28260 at a moderator's request, which I questioned due to the lack of any signs of crashing when I found the bug; I have yet to receive a reply.

      Thus, I have decided to repost these here. The first bug is that the piston deletes the block it moves into. Upon closer inspection, it seems the piston extends, begins to retract but instantly begins moving, gets stuck in extended position with the arm inside of T2, then deletes the block when it decides to retract. This occurs when T1 is air and T2 is a normal block.

      The second bug is that the piston carries a block sideways then (the piston) turns into an item drop. Again, upon closer inspection the piston spits out T1, begins extending right as it is moved by the machine, gets its arm stuck in T2, proceeds to bring T2 to T1's starting location as the piston is moved back, then the piston drops itself as an item. This occurs when both T1 and T2 are normal blocks.

      Both of these glitches appear to stem from extending/ed pistons remaining movable if powered in a special way.

      World download: MCPE-30805.mcworld

      (!)Warning: Using Note Blocks creates a chance for the game to crash. This seems to be limited to just Note Blocks for now.

      A schematic (with original coordinates) of the original machine is below:

      Facing positive z, x (left): 165, x (right): 161
      z: 10

          RB SB RB
      [RB] P> PA SB <P

      z: 9

        NB S*   NB

      z: 8

          T1 T2  


      > Left
      < Right
      v Down
      * Towards the screen
      NB Normal block
      RB Redstone block
      [RB] Remove this block to start the machine, replace to stop
      SB Slime block
      P Regular Piston
      S Sticky Piston
      O Observer
      T1, T2 Testing blocks, known to change the end result of the machine

      P.S.: Sorry mods, I just didn't feel like this was getting the right attention in what I consider to be a dead ticket and a separate and/or blanket issue.


        1. MCPE-30805.mcworld
          31 kB
        2. MCPE-30805 v2.mcworld
          33 kB
        3. Minecraft 1_22_2018 6_40_44 PM (Edited).mp4
          7.58 MB
        4. Minecraft 1_22_2018 6_55_52 PM.mp4
          3.09 MB
        5. Note block crashes.xml
          5 kB

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