How to Repair Corrupted Chunks & Crash Loops Without Wiping Your World

A single corrupted item entity, malformed NBT tag, or broken tile entity inside a chunk can crash your Minecraft server every time a player walks into that area. If your server is stuck in a continuous crash loop whenever someone logs in, this step-by-step technical guide will teach you how to isolate and repair corrupted region files without deleting your world build.

Step 1: Locate Crash Coordinates in Server Crash Reports

When a server crashes due to a corrupted chunk, open the latest file in your crash-reports/ directory. Scroll down to the Details section and search for the following key lines:

-- Block entity being ticked --
Details:
    Name: minecraft:chest // or mob_spawner
    Block location: World: (-412,64,185)
    Chunk location: World: (Block: -412,64,185), Region: (-1,0; in -1,0)

Write down the exact Block X, Y, Z coordinates and the **Region File name** (e.g. r.-1.0.mca).

Step 2: Understanding Region File Math (.mca)

Minecraft divides world dimensions into region files saved inside the region/ folder. Each .mca file contains a 32x32 grid of chunks (512x512 blocks):

• Chunk X: Math.floor(Block X / 16) → e.g. Math.floor(-412 / 16) = -26
• Chunk Z: Math.floor(Block Z / 16) → e.g. Math.floor(185 / 16) = 11
• Region File: r.{Math.floor(Chunk X / 32)}.{Math.floor(Chunk Z / 32)}.mca → r.-1.0.mca

Step 3: Repairing the Corrupted Chunk using MCA Selector

1. Stop your Minecraft server completely. Always create a full ZIP backup of your world folder first!
2. Download and launch MCA Selector. Click File → Open World and select your world's region/ folder.
3. Type your corrupted chunk coordinates into the top search bar (e.g. Chunk X: -26, Chunk Z: 11).
4. Select the corrupted 16x16 chunk grid.
5. Click Selection → Delete Selected Chunks (or Selection → Clear Entities if you only want to remove broken mobs/items).
6. Save changes and restart your server.

Minecraft will safely regenerate a fresh, uncorrupted chunk at that location when players return, preserving the surrounding builds!

Verify Bedrock and Java pack manifest files before loading custom worlds with our Manifest Generator!