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Unable to load chunk / Exception ticking world (corrupt region file)

When every boot (or every visit to one area) crashes with an exception naming chunk coordinates, the usual suspect is one corrupt region file — the container holding 32×32 chunks. Worlds are thousands of regions; losing or repairing one saves the rest.

Fastest path: paste your crash report into the Crash Doctor — it identifies this pattern and 40+ others automatically. No signup.

How to fix it

  1. 1

    Get the chunk coordinates from the log

    The exception names a chunk or block position. Convert to the region file: region file r.X.Z.mca where X = chunkX >> 5 and Z = chunkZ >> 5 (integer division).

  2. 2

    Restore that region from backup

    From a world backup, copy out the matching r.X.Z.mca into the live world/region folder (with the server stopped). Everything around it stays live-state.

  3. 3

    No backup? Trim the region

    A region-editor tool can delete the bad chunks; the area regenerates as new terrain. Neighboring builds are untouched — only the corrupted section reverts.

  4. 4

    Check disk health and shutdown hygiene

    Corruption usually traces to a crash mid-write or a failing disk. Verified backups plus clean shutdowns turn this from a disaster into a five-minute fix.

Alternative causes

These can produce the same error message — worth ruling out if the steps above don't resolve it.

Entity overflow in one chunk

Hundreds of entities ticking in one spot crash the tick loop without any corruption — the ticking-entity guide covers that pattern.

World opened across incompatible versions

Downgrading a world to an older MC version corrupts data structures. Keep worlds moving forward only.

Frequently asked

Will deleting the bad chunk lose my builds?

Only inside the deleted region, which regenerates as fresh terrain. Adjacent regions and builds are untouched — this is why isolation beats world-wide fixes.

How do I find the chunk coordinates in the log?

Look for lines naming a block or chunk position near the exception. The conversion to region files is integer division by 32 on both axes.

Can hosts prevent region corruption?

Not entirely — but verified backup restores and clean shutdown handling reduce it to a routine recovery instead of data loss.

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Last reviewed 2026-09-06. If a step is wrong or out of date, tell us — we'll fix the article and the auto-pattern at the same time.