NbtAccounterException: Tried to read NBT tag with too high complexity, depth > 512

[Schneidertm]

Stack trace

https://mclo.gs/GZirUfn

Plugin and Datapack List

Paper Plugins (9): CraftBook5, HuskHomes, LiteEco, MiniCmd, MiniGuard, MiniLog, SignRewards, VaultChatFormatter, VillagerLobotimizer
Bukkit Plugins (34): Bolt, BoltWorldGuard, ChunkSpawnerLimiter, Chunky, ChunkyBorder, ColoredSigns, DiscordSRV, dynmap, EntityDetection, FlyingCarpet, ImageFrame, LogBlock, LogBlockQuestioner, LuckPerms, mcMMO, Multiverse-Core, Multiverse-Portals, OpenInv, packetevents, PremiumVanish, ProtocolLib, QuickShop-Hikari, RedstoneClockDetector, SafariNet, ServerLinksZ, UnifiedMetrics, Vault, ViaVersion, VoidGen, Votifier, Vulcan, WorldEdit, WorldGuard, ZHorse

[Fri 23:22:47 INFO Server] There are 6 data pack(s) enabled: [vanilla (built-in)], [file/bukkit (world)], [file/invisibleitemframe (world)], [file/sit (world)], [file/minicraft (world)], [paper (built-in)]
[Fri 23:22:47 INFO Server] There are no more data packs available

Actions to reproduce (if known)

On 11. Feb 2026 I noticed first a chunk reset on my server spawn. I did recover it from an backup and it did work for a few weeks. In the past Weeks the chunk doesnt hold any longer. Its get resetted almost every day.

The chunk does hold 3 chests. Two with 3 books each containing 43 pages about our server (first steps, warps, guidelines) full of NBT data. And one chest with 3 maps containing qr codes built block by block in a flat world.

Paper version

1.21.11-130-ver/1.21.11@c5a2736 (2026-04-11T11:14:19Z) (Implementing API version 1.21.11-R0.1-SNAPSHOT)

Other

No response

[electronicboy]

Well, you have data which is too nested inside of that chunk, you would need to inspect those chunk files and try to work out the culprit

[Schneidertm]

Thanks for the fast response! I understand. I did report it because it's a change within version 1.21.11. I updated my server to Minecraft 1.21.11 at Christmas, and the chunk resets began in February. The chunk itself has been untouched for years as it's a protected spawn area.

I think the books might be old with badly converted NBT data. I have moved them out of the chunk. I hope that solves the issue. If this is too much of an edge case, please feel free to ignore and close the issue.

[electronicboy]

Them un/loading consistently shouldn't really cause the data on them to change, mojang did start enforcing stuff more around NBT complexity in the past few versions, but, it happening after some period of time would suggest that you have something that's causing the data to be modified a lot; I do maybe semi recall a plugin or two in the past few months which caused wierd data embedding due to some changes, but, as said, you'd really need to look at the data in the chunk