Long NBT Killer
Prevent minecraft from crashing while encountering deep nbt tags
About this Mod
Introduction
When Minecraft is encountering any compound / list nbt tag with a depth greater than 512, it throws an exception and refuses to load the save.
This mod replaced the annoying mechanism with a harmless log warning, and let the game go ahead.
ATTENTION
- A compound / list nbt tag with a depth greater than 512 itself is abnormal, and you may check your save via NBT editor after receiving the warning in the log;
- You DEFINITELY CAN add the mod to your modpack.
Available Versions
How to Install Long NBT Killer on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.8).
Install Mod
Open the mod browser in the dashboard and search for "Long NBT Killer". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.8, 1.21.3, 1.21.2 (+3 more)
Server-side
✓ RequiredRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
Long NBT Killer server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.21.8). You can switch loaders with one click in the panel.
Is Long NBT Killer compatible with fabric and forge and neoforge?
Long NBT Killer officially supports fabric, forge, neoforge for Minecraft 1.21.8, 1.21.3, 1.21.2. Note: Forge and Fabric mods are NOT cross-compatible – pick one loader and stick with it. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with Long NBT Killer – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Long NBT Killer consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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