1.20.6: Failed to save entity data

[Brokkonaut]

Expected behavior

Chunks should save (maybe by removing invalid characters from profiles) or creating invalid profiles should be prevented by the api.

Observed/Actual behavior

Invalid profiles can be created but chunks that contain entites with itemstacks with invalid profiles don't save at all. Paper sends a "Failed to save entity data (8,-6) in world 'freebuild'" message in the logs, but no stack trace, so i patched paper to add a stack trace there:

[00:43:39] [Server thread/ERROR]: [NewChunkHolder] Failed to save entity data (8,-6) in world 'freebuild'
net.minecraft.ReportedException: Saving entity NBT
at net.minecraft.world.entity.Entity.saveWithoutId(Entity.java:2570) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Entity.saveAsPassenger(Entity.java:2388) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Entity.saveAsPassenger(Entity.java:2374) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Entity.save(Entity.java:2404) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.level.chunk.storage.EntityStorage.lambda$saveEntityChunk0$0(EntityStorage.java:121) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[?:?]
at net.minecraft.world.level.chunk.storage.EntityStorage.saveEntityChunk0(EntityStorage.java:109) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.level.chunk.storage.EntityStorage.saveEntityChunk(EntityStorage.java:100) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at io.papermc.paper.world.ChunkEntitySlices.save(ChunkEntitySlices.java:108) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at io.papermc.paper.chunk.system.scheduling.NewChunkHolder.saveEntities(NewChunkHolder.java:1924) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at io.papermc.paper.chunk.system.scheduling.NewChunkHolder.save(NewChunkHolder.java:1791) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at io.papermc.paper.chunk.system.scheduling.ChunkHolderManager.autoSave(ChunkHolderManager.java:227) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.level.ChunkMap.saveIncrementally(ChunkMap.java:535) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.level.ServerChunkCache.saveIncrementally(ServerChunkCache.java:437) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.level.ServerLevel.saveIncrementally(ServerLevel.java:1499) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1598) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1237) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:326) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.IllegalStateException: Player name contained disallowed characters: 'Minesweeper Tile'
at com.mojang.serialization.DataResult$Error.getOrThrow(DataResult.java:275) ~[datafixerupper-7.0.14.jar:?]
at com.mojang.serialization.DataResult.getOrThrow(DataResult.java:79) ~[datafixerupper-7.0.14.jar:?]
at net.minecraft.world.item.ItemStack.save(ItemStack.java:615) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Display$ItemDisplay.addAdditionalSaveData(Display.java:700) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Entity.addAdditionalSaveData(Entity.java:2735) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
at net.minecraft.world.entity.Entity.saveWithoutId(Entity.java:2518) ~[paper-1.20.6.jar:git-Paper-"3fc9358"]
... 18 more

Steps/models to reproduce

Looks like some plugin created a head with an invalid profile name (containing spaces?)

Plugin and Datapack List

n/a

Paper version

[00:59:58 INFO]: This server is running Paper version git-Paper-"3fc9358" (MC: 1.20.6) (Implementing API version 1.20.6-R0.1-SNAPSHOT) (Git: 3fc9358)
You are running the latest version

Other

No response

[Machine-Maker]

This is going to be on the plugin to fix. Player profiles on itemstacks (in skulls) have very strict constraints that the server can't just change. They are enforced on the client too during packet deserialization.

[Brokkonaut]

I know it has to be fixed in the plugin, but i definitely think the api should prevent profiles like that to avoid data loss later

[Machine-Maker]

Oh, yeah I think we missed adding a check for characters. We added only the length check, I thought we added both and this plugin was just not using the API.