Chunks switched places

Can you please attach the game logs from when the issue happened? You can find them in .minecraft/logs.

I added all logs from that day. I dont really know which one is important here. The accident could happend in second one probably and then i was trying to load my world two times. Thanks

Extracted from 2019-10-12-1

2019-10-12.log

Exception loading structure piece with id minecraft:nvi
java.lang.NullPointerException: null
	at ccq.<init>(SourceFile:28) ~[19w41a.jar:?]
	at ccq.a(SourceFile:53) ~[19w41a.jar:?]
	at chs.<init>(SourceFile:44) ~[19w41a.jar:?]
	at chy$$Lambda$1133/1982672460.deserialize(Unknown Source) ~[?:?]
	at abf.a(SourceFile:18) ~[19w41a.jar:?]
	at clb.<init>(SourceFile:48) ~[19w41a.jar:?]
	at cfe$a.<init>(SourceFile:35) ~[19w41a.jar:?]
	at cez$$Lambda$1069/219564344.load(Unknown Source) ~[?:?]
	at clf.a(SourceFile:80) [19w41a.jar:?]
	at cam.a(SourceFile:419) [19w41a.jar:?]
	at cam.a(SourceFile:175) [19w41a.jar:?]
	at wm.j(SourceFile:511) [19w41a.jar:?]
	at wm$$Lambda$2855/408462158.get(Unknown Source) [19w41a.jar:?]
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1582) [?:1.8.0_51]
	at aik.h(SourceFile:144) [19w41a.jar:?]
	at aik.v(SourceFile:118) [19w41a.jar:?]
	at wy$a.v(SourceFile:550) [19w41a.jar:?]
	at wy.d(SourceFile:274) [19w41a.jar:?]
	at net.minecraft.server.MinecraftServer.aZ(SourceFile:726) [19w41a.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:714) [19w41a.jar:?]
	at aik.bj(SourceFile:103) [19w41a.jar:?]
	at net.minecraft.server.MinecraftServer.u(SourceFile:698) [19w41a.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:654) [19w41a.jar:?]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51]

Please check if that's still an issue in 19w46a.

This bug is not something that can be easily reproduced.

This ticket has been merged into MC-161823.