I have discovered what seems to be an unreported but critical chunk corruption issue that is present at least in the newly released 1.20.30 Bedrock on Windows 10 and 11 (tested on both).
The image below shows what the corruption looks like. It looks like the chunks are mis-generated in 1.20.30 compared to 1.20.15, which is the second screenshot below. I'll provide some details on how to reproduce this bug and the world saves, as it can be consistently reproduced.
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Reproduction steps:
Generate a new world in Minecraft 1.20.15. In this case, I used the seed 7671300184158697625
Because the issue seems to be visually easier to confirm in mountain biomes, I teleport to the coordinates show in the screenshots above. Now exit the game.
Update to Minecraft 1.20.30 (this can be done using the unofficial Minecraft bedrock launcher to more easily reproduce, but the same issue also happens even without using the unofficial launcher). Load the world again and return to the same coordinates. The corruption shown in the screenshot above will appear, although not necessarily in the exact same spots.
From digging deeper my understanding of the problem is the following.
-Minecraft doesn't save all chunks that are visually present, just the ones you interact with or are closer to you, so not all chunks in the 1.20.15 screenshot without the issue have actually been fully generated and saved, even though visually all are present. These "missing" chunks can be confirmed by using a tool like unmined.
-After updating to 1.20.30 and returning to the same spot, the chunks that were "missing" in 1.20.15 are now being generated in 1.20.30, which for some reason, generates these chunks differently. This is basically the bug.
Some other additional information:
-This bug might have been around for a while, I tried the 1.19 to 1.20.15 transition and was also able to reproduce the issue.
-Strangely enough, there seems to be a limited fix via the official chunker.app online tool. I had a world where these mountains (minus the "missing" chunks) were generated in 1.19, updating the game to 1.20.15 and returning to this region would actually manifest this problem. However, if before returning to this region (and triggering the generation of the "missing" chunks), one uses the chunker.app tool to convert the now 1.20.15 world, to the exact same version (by picking 1.20.10 in the chunker menu), if you return to this region, the "missing" chunks now generate properly. So the chunker conversion has done something to "fix" this problem. However, strangely enough, this does not work if converting to version 1.20.30 in chunker (so maybe the same bug manifest itself in chunker as well).
Finally, I have also attached the world download. The 1.20.15 file is the world save from the image without the problem while the 1.20.30 file is the world save from the image with the problem.
I believe this issue is critical because 1.20.30 just got rolled out and everybody who generates new chunks on it will have this problem and corrupt their world.
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GoldenHelmet
This is not chunk corruption. "Corruption" usually refers to parts of a chunk or an entire chunk being voided.
Nor is this a critical issue. It does not make the game unplayable or cause irreparable loss of players' progress.
This is just imperfect blending between chunks generated in different versions. That has always occurred to some degree. Perhaps it is a little worse now than in 1.18 per this report and MCPE-154061. Perhaps that is a result of the fix for MCPE-149474.
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I would beg to differ. Having the landscape torn up like that really breaks the immersion.
This is also not a blending issue. If you were to generate the exact same seed and location using 1.20.30, it actually generates block by block identical to 1.20.15, which is the expected behavior because the chuck generation did not change between these two versions.
It only generates differently when it is a 1.20.15 world being loaded in 1.20.30, so that is clearly a bug. The reproduction steps are pretty clear and on two separate devices, I've been able to reproduce this 100% of the time.
Edit: I think the changed title is actually less accurate, because there is not supposed to be any blending between 1.20.15 and 1.20.30 as the terrain generation did not change. This can be demonstrated by generating the same terrain in both versions to confirm.
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I would beg to differ. Having the landscape torn up like that really breaks the immersion.
This is also not a blending issue. If you were to generate the exact same seed and location using 1.20.30, it actually generates block by block identical to 1.20.15, which is the expected behavior because the chuck generation did not change between these two versions.
It only generates differently when it is a 1.20.15 world being loaded in 1.20.30, so that is clearly a bug. The reproduction steps are pretty clear and on two separate devices, I've been able to reproduce this 100% of the time.
Edit: I think the changed title is actually less accurate, because there is not supposed to be any blending between 1.20.15 and 1.20.30 as the terrain generation did not change. This can be demonstrated by generating the same terrain in both versions to confirm.
GoldenHelmet
Thank you for the clarification. I have adjusted the summary again to hopefully be more accurate. I would still say that the discontinuity between the chunks shown in your screenshot is far less than what I have see all over my worlds ever since I’ve been playing Minecraft, but it sounds like there may be a bug in with the detection of when and how blending should be performed.
GoldenHelmet
Could you provide a screenshot of the full 1.20.30 generation? Despite foreground similarity, the mountain peaks in the top left and top right of the provided screenshots look very different, which makes me think generation may have changed.
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I don't have a 1.20.30 screenshot handy, but I did do this check over the weekend when I was looking into this, and I can confirm that 1.20.30 and 1.20.15 generation is identical block for block. This is easy to confirm, just create a new world with this seed in 1.20.30 and visit these coordinates and you will find it is actually identical to my 1.20.15 screenshot.
The bug however appears when chunks that were not saved in 1.20.15 are subsequently generated in 1.20.30.
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I don't have a 1.20.30 screenshot handy, but I did do this check over the weekend when I was looking into this, and I can confirm that 1.20.30 and 1.20.15 generation is identical block for block. This is easy to confirm, just create a new world with this seed in 1.20.30 and visit these coordinates and you will find it is actually identical to my 1.20.15 screenshot.
The bug however appears when chunks that were not saved in 1.20.15 are subsequently generated in 1.20.30.
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I have the same bug with 1.20.40
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I have the same bug with 1.20.40
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There seems to be a "fix". I noticed there is a bugfix in chunker.app version 1.19.10 which is addressing some chunk blending bug in 1.20.30. So chunker might have fixed the bug that is still present in bugrock.
The "fix" steps are as follows.
Take your 1.20.15 world and move to a location where all the chunks are already generated (so bad chunks don't get generated in).
Update bedrock to 1.20.30 (using the unofficial bedrock launcher is a good way to do this) and load in the world, and then save the game. Now your 1.20.15 world is a 1.20.30 world.
Export your 1.20.30 world, and upload it to chunker.app, and convert it to the same version for the output (so 1.20.30). All entities will be lost, but at least you will keep your items.
Now update your bedrock to 1.20.40, and import the chunker converted 1.20.30 world. Now, new 1.20.40 chunks will generate properly, and the world gets updated to 1.20.40
No clue about how "stable" this fix is (it's possible that 1.20.50 will break things again), but it at least made it possible to get a 1.20.15 world up to the latest and get proper chunk generation again.
Note, after you have done steps 1-4, there is also a way to fix the previously generated back chunks if you have any in your world. Simply delete those chunks in Amulet, and then they will regenerate back in properly.
migrated
There seems to be a "fix". I noticed there is a bugfix in chunker.app version 1.19.10 which is addressing some chunk blending bug in 1.20.30. So chunker might have fixed the bug that is still present in bugrock.
The "fix" steps are as follows.
Take your 1.20.15 world and move to a location where all the chunks are already generated (so bad chunks don't get generated in).
Update bedrock to 1.20.30 (using the unofficial bedrock launcher is a good way to do this) and load in the world, and then save the game. Now your 1.20.15 world is a 1.20.30 world.
Export your 1.20.30 world, and upload it to chunker.app, and convert it to the same version for the output (so 1.20.30). All entities will be lost, but at least you will keep your items.
Now update your bedrock to 1.20.40, and import the chunker converted 1.20.30 world. Now, new 1.20.40 chunks will generate properly, and the world gets updated to 1.20.40
No clue about how "stable" this fix is (it's possible that 1.20.50 will break things again), but it at least made it possible to get a 1.20.15 world up to the latest and get proper chunk generation again.
Note, after you have done steps 1-4, there is also a way to fix the previously generated back chunks if you have any in your world. Simply delete those chunks in Amulet, and then they will regenerate back in properly.
SugarKingMC
I also encountered that issue too
Here's some screenshot