Minecraft world won't load: corrupted level.dat or region file
Last reviewed 2026-09-19
A Java Edition world keeps its settings in level.dat (a compressed data file) and its terrain in region (.mca) files of 1024 chunks each. A damaged level.dat stops the whole world from loading, while a single bad chunk entry can crash or hang the game when you walk near it.
Messages you might see
- “World fails to load / the world shows as corrupted or broken”
- “level.dat is missing or unreadable”
- “The game crashes or hangs when entering certain chunks”
Why it happens
- The game or computer crashed while saving.
- A backup or sync tool copied the world while the game was writing to it.
- A failing disk or a cut-off copy damaged one file.
Try this first (free, no tool needed)
- Copy the whole world folder to a safe place before doing anything.
- Minecraft keeps a backup: rename level.dat to something else, then copy level.dat_old to level.dat and try again.
- Restore from any backup (launcher backups, your own copies, server backups).
- Make sure you are using the Java Edition; Bedrock worlds use a different format.
If that didn't work
These tools run in your browser. Your file is read and repaired on your own device and is never uploaded.
Corrupted Minecraft World Repair
For level.dat and other .dat files: reads as much as survives, even from a cut-off gzip, writes a valid file and summarises the world (name, version, seed, spawn). For region .mca files it checks all 1024 chunk slots and clears the bad ones so the game regenerates only those chunks. Data that is not in the file cannot be recovered, so keep a copy of your world. Java Edition only.
Open Corrupted Minecraft World RepairCommon questions
Will I lose the chunks it clears?
Yes: a chunk that could not be read is cleared and the game generates it again, which loses anything built there. Only unreadable chunks are touched.
Is my file uploaded anywhere?
No. The tool runs as a program inside your own browser, so the file is read and repaired on your device and never sent to a server.