Chunks sometimes are dislocated / copied to another location

I assume you converted your world from 1.13.2 to 1.14. If you have backed up your world before converting it to 1.14, can you attach the back up? If the file size is too large, please upload it somewhere else and then link to it here.

I have experienced the same issue. I had created a new world in 1.14 when it came out and beginning this week chunks have been switched around when I log back into the world. I'm too worried to go back into the world and making it worse. The problem hasn't fixed itself either and I don't know the cause.

Also, how much free storage space is left on your disk? This might be caused by not enough space on the disk to store the world properly (see MC-74762)

The same thing has been happening to me for almost a week. I have more than half of my space left on my disk and for the past two days the problem seemed to be fixed. But when I logged on today, it was twice as bad as usual, and it's the same world I created in 1.14. Should I delete things off my disk or is it a bug?

It was a brand new 1.14 world. plenty of space on the computer. it just kept getting worse every time i logged on. Haven't been on it in a while tho

Had the exact same thing in my world (originally 1.13). Plenty of room on the disk. I added my logs and screens.

+1. this also happened me yesterday while changed from Paper to another software. Chunks just moved somewhere on every world by loading another world. fix in 1.14.3 please

Well, logs please. So far we've been unable to reproduce this. Also, "Paper to another software" is very vague. And third-party software does not make debugging easier.

This is a backup of our region file which does reproducibly cause the chunks to re-locate. Sadly, this may be due to previous saving of the chunks and I am unable to provide the world as it is too large. I do however, have 570+ backups of the world so might be able to trace back if required.

-7750, -180 will bring you to the region file's location.

Note: The backup was taken a few hours before the issue occurred.

In the Minecraft logs you can see:

Chunk file at [X1, Z1] is in the wrong location; relocating. (Expected [X1, Z1], got [X2, Z2])

All chunks in that file were last saved in 1.13.2 (somewhere between 2019-04-25T11:42:38Z and 2019-04-26T05:52:47Z, might be actually interesting to see backup and maybe logs from that time), 15 of them already in wrong positions. Also, all of them are duplicates of some other position, there are no swaps.

I would guess it may be instance of MC-74762, though that one seems to be more about problems caused by lack of space or write errors.

Also experienced this using --forceUpgrade from 1.13.2 to 1.14.3.  

Could you provide the world before and after the update, please, together with logs and what you did apart from upgrading with --forceUpgrade (if you did anything else before it happened)? This might be a good example to reproduce the issue which would help the devs lots, I guess...

I updated from 1.14.3 to 1.14.4 and this is happening to me as well

This or simila bug was hapening to me in all past versions when i quickly swich to another world especialy if i create new one.
i used low end computer at that time if that could help anyhow.
1.4 1.5.2 1.6 1.7.2 1.7.4 1.7.10 1.12.2

Bigest chance was when i make new world, after 10 seconds make new world. it copyed chunks from world 1 to world 2 at that time.

Could it be that the RegionFileCache is still valid and filled when switching worlds or reloading the same world in case of a slow computer or heavy lag? Maybe clearing the cache inside RegionFileCache.close() after closing all RegionFiles could help then?

This has been happening to me to, just had a survival world I spent days on totally destroyed. This really needs to fixed, it gets very frustrating the more it happens to me. I’ve had a total of 5 different worlds destroyed from this bug. So please fix this devs, i’ve been a long time playing and I kind of feeling like quitting the game because of how much time i’ve spent on my worlds just to have them destroyed. Fix your game. (This is happening on 1.14.4 I forgot to mention that)

Yup, just got this issue. Unfortunately I don't have a backup of the world that it happened in. This appeared in the log:

[14:12:37] [Server thread/ERROR]: Chunk file at [-1, 0] is in the wrong location; relocating. (Expected [-1, 0], got [-2, 1])
[14:12:37] [Client thread/INFO]: Preparing spawn area: 0%
[14:12:37] [Client thread/INFO]: Preparing spawn area: 0%
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3243, l='mooshroom', x=-25.36, y=72.77, z=27.30]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3244, l='mooshroom', x=-21.11, y=72.77, z=26.09]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3245, l='mooshroom', x=-23.66, y=72.70, z=30.30]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3246, l='mooshroom', x=-20.94, y=72.62, z=29.82]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3247, l='mooshroom', x=-28.75, y=72.76, z=26.17]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3248, l='mooshroom', x=-19.81, y=72.48, z=31.88]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3249, l='mooshroom', x=-23.29, y=72.44, z=31.88]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3250, l='mooshroom', x=-19.86, y=72.40, z=28.69]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3251, l='mooshroom', x=-21.23, y=72.49, z=23.10]
[14:12:37] [Server thread/WARN]: Wrong location! (-2, 1) should be (-1, 0), atx['Brown Mushroom'/3252, l='mooshroom', x=-20.69, y=72.46, z=24.87]

It should be noted that I used the NBT editor in order to change the biome of the chunk that was being copied, but that shouldn't have changed anything(?) Maybe using NBT editing I can find the cause of this. Will test further.

Would it be possible to add a short description when an issue is resolved, so we could know what caused it and maybe how to prevent it until the fix gets rolled out? Thank you!

Not really, as this seems to have been caused by a race condition in the code of the game, which is not something that you can work around.

But if we knew some more details, we could maybe avoid certain situations that are more likely to trigger it, e.g. if the race condition only happens on server shutdown or start, on dimension change etc., what log output to look out for if there is any and so on. Not just for this bug report, but in general. I don't know how many would be interested in such more detailed information and if you can provide it, and I know this is not the right place for a discussion about it, but it would be cool if that could be considered where appropriate. Thank you ^^

There is no general way to trigger that, and we had no luck in actually reproducing this, so everything we could do is just making that code saner. We changed a code to keep file consistent even in case of write failure. Such failure would leave warning log, so I guess you can look for that. I don't claim it's 100% fixed, but corruption should be rarer and easier to diagnose and recover.

That's good to know, thank you, also for taking the time to fix so many things for the next update!

I just started playing my new 1.14.4 world and I am having the same problem where the chunks are loading in different place I am running the latest version of java and have more than half of my computer storage free so if you have any suggestions on how I can resolve this problem can you please let me know this been happening for more than a month now and I have had to delete so many worlds.

This issue will be fixed in 1.15. If you have made backups of your world, you can restore your world using those. If you don't, unfortunately your world will be corrupted and cannot be restored to its original state.

If you encounter this issue in a 1.15 snapshot, please create a new ticket and include as much information (i.e., game logs from when this issue happened) as possible.

I also want to mention my achievements reset when i login to my world and that happened.

Just fyi we were experiencing this issue on our 1.14.4 servers in the past few weeks very often. I decided to look into what changed between 1.14.4 and 19w36a (as this is the first version with obfuscation mappings). I noticed that the RegionFile class has been completely rewritten. So I decided to implement the new RegionFile code into the 1.14.4 server. At first this seemed to have fixed the issue, but today the issue appeared again. And yes I am using a custom server software, but the issue is extremely likely to be the vanilla issue and if the code changes that were mentioned above are those in the RegionFile class, it seems like they did not fix the issue. I will look into what else changed and see if I can implement that too. I noticed that there were some changes in chunk de-/serialization too, but I think this is only due to the changes in the biome format.
You won't have to tell me that I would need to reproduce this on a proper 1.15 server for a proper bug report. However I won't be able to do so. Worlds get loaded thousands of times per day on our 1.14.4 server which makes it way more likely for the issue to occur. I just don't have a similar setup for 1.15 yet.

If you're able to reproduce this issue in 1.15 (or the 1.15 snapshots), please leave a comment in MC-161823.