[MCPE-194207] When ray tracing is enabled placing or breaking blocks causes surrounding blocks to flicker

When breaking or placing blocks with ray tracing enabled, surrounding blocks flicker.

Steps to Reproduce:

Load any ray tracing-capable resource pack.
- Optimally use an empty RT capable resource pack, there is one attached for convenience.
Enable ray tracing and join a world.
Break or place blocks and observe flickering.

Evidence video attached.

Notes:
There is another old bug that makes enabling RT difficult, to turn it on properly before testing:

Activate RT-enabled pack.
Join a world.
Turn on ray tracing through video settings
Exit to menu and rejoin.
Then test for this bug.

This bug started happening in 1.21.70 Previews and persists in 1.21.70 release and 1.21.80 Previews

Linked issues

is duplicated by 3

MCPE-194362 Chunks Flickering With Ray Tracing Resolved

MCPE-206064 RTX issue, Blocks flashing when updated, started with spring to life update Resolved

MCPE-227816 Flickering While Digging & Building With Ray Tracing Enabled Resolved

Attachments

Empty-RT-Capable-RP.mcpack

Comments 15

MADLAD 2025-03-26T19:03:31Z

Attaching a video of the issue from my duplicate report:

JohnnyTamale1 2025-04-03T03:22:19Z

Looks like it’s chunk updates causing the bug, not just placing and removing a block.

Here’s a video of this happening with Redstone. https://streamable.com/c54lzx

Cubeir 2025-04-07T12:53:30Z

Updating a block’s state (e.g. switching a vault block between active and inactive states constantly) should also be causing this if chunk updates were the trigger.

Redstone contraptions that move blocks do trigger this glitch, while block updates do not seem to.

If a block (other than air) is already placed, replacing it for instance via setblock command should not trigger this issue.

For now placing by hand is the most reliable way to reproduce this issue.

Fionn Croke 2025-04-21T05:18:50Z

Having the exact same issue, very frustrating. When mining in the nether I feel like I’m playing in x-ray mode being blinded by a strobe of flashing images

godclo 2025-04-26T19:46:57Z

Sometimes when i restart my game it fixes this bug

5 more comments

MADLAD 2025-05-08T04:17:13Z

Confirmed this issue affects stable release 1.21.80, it really should be fixed soon. May pose a photosensitivity hazard.

Steve 2025-05-08T05:45:50Z

Can confirm that I am compelled to disable RTX when mining due to the strobing/flashing effect caused by this bug. Minecraft should come with a warning.

Fionn Croke 2025-05-09T11:05:10Z

I’m surprised people are only reporting this now, I’ve had this issue with RTX for a long time.

Fearlove 2025-05-16T06:45:30Z

pls fix it, i cant play the game without rtx😭

WeatherTheMCReporter 2025-05-21T06:53:44Z

Further analysis
Key Observations:

This is not unique to the Windows Platform. The same issue occurs on Minecraft Education Preview 1.21.80.1 and by consequence, GNU/Linux (Wine) as well.
This bug is not uniform, and it doesn’t affect every world. It only affects some worlds, particularly ones that are large in size.
This bug does affect gameplay heavily and pretty much makes playing the game unplayable on worlds with a lot of moving blocks loaded within a chunk

Technical breakdown:

This bug is caused by a heap overflow within the game when it comes to calling irradiance cache updates. This is evident because in the snapshots captured during the time frame in which this bug occurs, RtlAllocateHeap fails. The game manages to correct itself and rellocates the buffer in order to avoid crashing.

P.S: It’s surprising this passed CI.

Nguyen Van Hai 2025-06-05T17:43:13Z

Hello, why this isnt fixed yet, this is a game breaking bug. Affect all rtx enabled player

Minizekrom 2025-06-13T11:41:36Z

Yeah this is really bad, especially painful when strip mining or quickly mining sand etc…

Tofulisk 2025-06-19T01:23:05Z

This seems to happen for any block update - including pistons that move blocks.

Cubeir 2025-09-07T19:03:17Z

In a game that’s fundamentally about placing and breaking blocks, one would expect issues such as this would be resolved in basically no time, building is genuinely painful now in my experience.
Is everything okay at Mojang?

SmartAngel 2025-09-10T10:09:36Z

Still affected 1.21.101 Hotfix.

The video from my duplicate report.