[MCPE-16093] MCPE Crashes frequently when a minecart that is activating a detector rail and that dector rail are pushed by pistons at the same time Created: 06/Jul/16  Updated: 21/Oct/16  Resolved: 21/Oct/16

Status: Resolved
Project: Minecraft (Bedrock codebase)
Component/s: None
Affects Version/s: 0.15.1, 0.15.2, 0.15.90.2
Fix Version/s: 0.15.90.8

Type: Bug
Reporter: inxomnyaa
Resolution: Fixed Votes: 2
Labels: crash

Attachments: PNG File IMG_0222.PNG     PNG File Screenshot_2016-07-07-08-49-48.png     JPEG File photo_2016-07-06_22-21-31.jpg    
Confirmation Status: Confirmed
Platform: Windows
CHK:

 Description   

Whenever any minecart is on a detector rail (powering the rail) and some piston contraption causes both the minecart and the detector rail to be pushed (works fine on pull, crashes only on push) then MCPE is likely to crash. The crash does not happen every time, and with different builds, it happens more or less frequently (suggesting this bug has something to do with redstone tick order of operations).

To reproduce

  1. float a piston (sticky or not, doesn't matter) above the ground pushing a slime block horizontally
  2. attach any solid block above the slime block (so the piston will push this block because it is stuck to the slime block)
  3. attach any solid block on which a rail can be placed beside the slime block, in line with the piston (so the piston will push this block too)
  4. place a detector rail on the previously placed block (the orientation of the rail relative to the piston push direction seems to matter. If the rail points perpendicular to the direction the piston pushes, the game crashes more frequently.)
  5. place any minecart on the detector rail, activating it
  6. activate the piston by any means
  7. MCPE has a high probability that it will crash to menu

Note: The above build is not the most general case, but does crash with high frequency. Slime blocks are not required to reproduce this crash. You can also stack two pistons, use redstone to trigger them at the same time, place one block in front of the bottom piston, place the detector rail and minecart on that block, and activate the group of pistons. This is illustrated in the second screenshot showing the pistons and the rail pointing the same direction as the push.



 Comments   
Comment by Zeb [ 08/Oct/16 ]

Appears to be fixed in 0.15.90.8.

Comment by rplatham [ 06/Sep/16 ]

Reconfirmed on Samsung Galaxy S6 (SM-G920W8), Android 6.0.1 MCPE 0.15.90.2.

Comment by Muhammet Mehmet Emin Kartal [ 04/Sep/16 ]

It crashes game when button is pressed.
iPhone 6s+ ios 10 beta 7

Comment by inxomnyaa [ 07/Jul/16 ]

Sorry, i did only test with slime blocks.

Comment by rplatham [ 07/Jul/16 ]

Confirmed on Samsung Galaxy S6 (SM-G920W8), Android 5.1.1 but you've got the build description all wrong. I'm updating the ticket now. Next time, be VERY specific about the build so we do not waste time trying to reproduce it.

Comment by inxomnyaa [ 07/Jul/16 ]

Same thing. But i realized that the minecart has to be pushed too, build it exactly like in the screenshot

Comment by inxomnyaa [ 07/Jul/16 ]

Removed unnessesary screenshots.

Well, the bug only appears for me when the minecart is on the track.
I'll try different rotations now, maybe its only south or something like that

Comment by rplatham [ 06/Jul/16 ]

Still confused here. I can't get the build in the screenshots to crash the game on:

  • Samsung Galaxy S6 (SM-G920W8), Android 5.1.1
  • Asus B121 Tablet touch & pen enabled, no keyboard or mouse, Win10 Pro x64 v1511 build 10586.420
  • Apple iPad3 (MC705C/A) iOS 9.3.2 (13F69)
Comment by rplatham [ 06/Jul/16 ]

There's already a ticket on the rail dup by piston push.

Comment by inxomnyaa [ 06/Jul/16 ]

Maybe you should test the behaviour yourself..
Because normal rail does drop but also stays, and drops totally when retracting,
other rails instantly drop duplicated, some not when retracting,
detector rails crash when minecart is on them and moved

Comment by inxomnyaa [ 06/Jul/16 ]

Hilarious, found an duplication bug also.

Comment by inxomnyaa [ 06/Jul/16 ]

Pushed the minecart off a bit just to show it

Comment by inxomnyaa [ 06/Jul/16 ]

Actually tried to simplify it, i'll attach a new screenshot

Comment by inxomnyaa [ 06/Jul/16 ]

Yea sure, i actually tried to create this machine https://www.youtube.com/watch?v=nYszbiYXMvM

Comment by rplatham [ 06/Jul/16 ]

Please post a screenshot of what you build before the crash or describe all the steps to build what you are describing. I was not able to reproduce your crash on my Samsung Galaxy S6 (SM-G920W8), Android 5.1.1 running MCPE 0.15.1.

I tried, in a new creative flat world, both sticky and regular pistons pushing from various different directions with normal minecarts on unactivated activator rails. None of my configurations crashed the game. I may have missed something, or this may just affect Win10, but we need more specific info to reproduce.

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