Diagnosing and Fixing Chunk Corruption

What Chunk Corruption Looks Like

The world is stored in 16×16 vertical slices called chunks. When a chunk's binary data goes bad, the engine throws on load. The classic stack trace:

[INFO] Chunk (42, -2) stored at (35, -28)
java.lang.Throwable
  at org.bukkit.craftbukkit.util.LongHashtable.get(LongHashtable.java:32)
  at net.minecraft.server.ChunkProviderServer.getOrCreateChunk(...)
  at net.minecraft.server.World.getChunkAt(...)
  at net.minecraft.server.World.getTypeId(...)

Symptoms in-game:

• TPS tanks the moment a player walks toward the bad coords
• World fails to save
• "World holes", unrenderable voids
• Plugins error when they touch the bad blocks

Fix It Without Losing The World

1. 1Stop the server (don't just kick players, full stop)
2. 2SFTP into the world folder
3. 3Find the region file containing the corrupt coords. Chunk → region math: regionX = floor(chunkX / 32), regionZ = floor(chunkZ / 32). For chunk (42, -2): region r.1.-1.mca
4. 4Back up that region file off-server
5. 5Open the world in MCEdit or MCC Tool Chest and delete just the bad chunk
6. 6Save → upload back → start the server
7. 7The engine regenerates the empty chunk cleanly from the seed

Players within ~512 blocks of the deletion will see a regenerated patch. Anyone living there: warn them first.

Catastrophic Corruption

If multiple regions are bad, the level.dat is broken, or the world won't load at all, restore from a backup. If you don't have one, see DriveBackupV2 setup.

Need More Help?

Paste the full stack trace in our Discord. We have admins who do this in their sleep.