☰

Heightmap Error

The server reports an invalid heightmap for a chunk. The cached surface-height data is wrong, usually from custom worldgen or a mod, and the chunk needs regenerating or recalculating.

What does this error mean?
Each chunk stores heightmaps (the top solid block per column) to speed up lighting and spawning. An 'invalid heightmap' means that cached data is inconsistent with the actual blocks, often after custom terrain generation or a worldgen mod wrote bad data. 
Invalid heightmap
Most Common Causes
  • Custom worldgen or datapacks producing inconsistent terrain data.
  • A worldgen mod writing invalid heightmaps.
  • Chunk data partially corrupted after a crash.
  • Version upgrades changing heightmap formats.
  • Manual world edits that left heightmaps stale.
How To Diagnose
  1. Identify the affected chunk coordinates from the log.
  2. Note whether custom worldgen, datapacks, or worldgen mods are in use.
  3. Check if the issue followed a version upgrade.
  4. Test with the worldgen mod/datapack removed.
Recommended Fixes
  • Regenerate the chunk
    Delete the affected chunk in MCA Selector so it rebuilds with correct heightmaps.
  • Remove faulty worldgen
    Disable the custom worldgen mod or datapack producing bad data.
  • Restore from backup
    Roll the affected region back to a known-good copy.
  • Recalculate heightmaps
    Use a world tool that can recompute heightmaps if you must keep the chunk.
Analyze My Log
Frequently Asked Questions

Usually minor, it mainly affects lighting/spawning in that chunk and is fixable by regeneration.

Heightmap formats can change between versions, occasionally flagging old chunks.

Yes for that chunk. Restore from backup if it contains something you want to keep.