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Tickwise
ErrorWorld & chunksSIG-WO-001

Corrupted chunks or region files: chunk data lost

Platforms
Paper · Purpur · single server
Verified
Verified
Confidence
Confidence 80%

What it looks like in the log

Any one of these lines is enough. The agent matches them locally, on your server.

logs/latest.log
  • [WARN] chunk data will be lost
  • [WARN] invalid sector at index
  • [WARN] regionfile
  • [WARN] is truncated: expected

Symptoms

  • Areas of the world have regenerated (builds are gone) or chunks fail to load
  • In the log: “Failed to parse/load chunk data for task … chunk data will be lost”, region file errors

Cause

The server could not read or parse chunk data from a region file (.mca). The chunk will be regenerated and any builds in it are lost. The cause is file corruption or data incompatible with the current version/world height.

Possible causes

  • The region file is corrupted: a crash/kill of the process during a write, a disk failure
  • The chunks were created by a different version/fork or with a different world height (datapack) and are incompatible with the current one
  • The world was copied/restored partially or with an external tool (MCA Selector, manual editing)

How to fixHigh risk

  1. Do not delete or “repair” world files on a running server; make a copy of the world folder first.
  2. Use the evidence to identify the world and chunk coordinates (world: …, chunk: (x,z), the path to r.X.Z.mca); region = floor(chunk_coordinate / 32).
  3. If you have a backup, stop the server and restore the affected region/r.X.Z.mca files from it (along with entities/ and poi/ for the same region).
  4. If there are many errors with nearby lines about a height/heightmap mismatch, check whether the server version, fork or world-height datapack was changed.
  5. Check the disk (SMART, free space) and never stop the server with kill — only stop.

Translated from the Russian original; log lines are quoted verbatim.

Sources