[MC-137961] Regenerating terrain in (unloaded?) chunks

Terrain regenerates itself when going from a pre-snapshot save to a snapshot file. The old buildings above ground are (with a few blocks missing or replaced) kept. I've tried recreating this bug twice on both snapshots, and I've tried it on 1.13.2. On 1.13.2 it shows no problems, but as you can see from the screenshots, it does have them on the newer versions.

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Comments 12

[Mod] Neko 2018-10-26T00:32:05Z

Was the world ever downgraded a version?

Jack 2018-10-26T16:23:46Z

The original world was created in 1.12, and I've only really upgraded it to 1.12.2 before, so I don't think it ever has.

David D 2018-10-26T17:56:49Z

I also experienced this - world was originally created in Version 1.7, and upgraded thru all the versions, currently running 1.13.1 with no issues. Never downgraded.

Upgraded from 1.13.1 version to snapshot 18W43b - The area and structures around initial player spawn in area (not the world spawn) appear ok but when I move into a unloaded chunk it seems that the terrain is regenerated and then merged into the existing world. Structures/blocks above the 'ground' level remain and are not replaced by air, but new terrain blocks replace the blocks from the previous world. Does not appear to be biome specific. I also noticed entities (item frames, wool, mutton, beef, etc) on the ground in the new chunks where the old buildings/sheep/cow farms were replaced by newly generated terrain

David D 2018-10-28T06:15:27Z

Just wanted to add that I upgraded 1.13.1 world to the 18W43C snapshot and this issue was resolved. Existing word terrain was not regenerated or altered, new chunks generated without issue and performance was greatly improved over the previous snapshots

Jack 2018-10-28T16:08:07Z

It's... somewhat fixed? The woodland mansion doesn't regenerate anymore, nor does the sea, but the area around the white building and tunnel still does. The only difference between the places is that the woodland mansion is where you spawn into the world, and the building in the sea has the worldspawnpoint. Also, when teleporting to the white building using command blocks, you end up around y12 or under bedrock. It seems to keep the y coordinate from before the chunks were done loading.

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2 more comments

David D 2018-11-21T22:00:31Z

I thought it was fixed because the one place that was replaced when I first found the issue was not messed with, but since you were still having problems I went back and checked more thoroughly and the problem still exists. I can also confirm this is still happening in the latest snapshot.

Upgraded a happy, working world from version 1.13.2 to the latest snapshot 18W47a using the Optmize World feature.

I think the initial terrain I am looking at was generated in version 1.7 or 1.8

The place where I spawned looked ok, but after closer inspection it looks like the initial chunk I load into stays ok (minecraft:mouontains and minecraft:birch_forest) but as soon as you move and start loading new chunks the biomes start to change

Before

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After

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Traveled out to a nearby preexisting village and what were plains biome has changed into a savannah biome and the new biome was overlayed atop the exsiting old structures and biomes.

If you look at the biome in the F3 in the before pictures in 1.13.2 it shows minecraft:plains and minecraft:wooded_hills
In the new snapshot it shows minecraft:savanna_plateu and minecraft:lukewarm_ocean!

It acts like the game does not recognize the older terrain was already generated and tries to generate new terrain, and since it is an older seed it does not generate the same biomes.

If I go underground under the spot where the biome now says ocean - everything below level 65 has been replaced by an ocean biome

Before

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After

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Before

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After Now an ocean biome

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Ocean biome under the ground

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Before was a plains biome with buildings is now a savanna_plateu

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Hope this can get fixed, I would hate to have to stop upgrading my world to the latest versions

Jason C. McDonald 2018-12-06T22:31:38Z

Having the same issue for a map coming from 1.13.2 (originally created in 1.7, I've been upgrading it successfully for years since.) It has regenerated terrain over some of my most important structures, and has actually changed entire biomes.

David D 2019-01-17T08:08:17Z

I just tested my old world in the 19w03a snapshot and am not seeing this issue any more. Seeing the correct biomes now and no re-generation of chunks.👍

Adrian Östergård 2019-04-04T10:21:06Z

Is this still an issue in 19w14a?

David D 2019-04-11T04:17:17Z

Looks like this issue has been resolved. Tested in 19w14b and 1.14 Pre-Release 1 and did not experience any problems

João de Camões 2019-04-12T18:08:18Z

I just had the issue in Pre-Release 2 (but it might have occurred in Pre-Release 1 already).

João de Camões 2019-04-12T18:09:48Z

Screenshot of the issue in Pre-Release 2 attached.

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