Invalid Biome Source
World loading fails because a biome could not be loaded. A datapack or worldgen mod references a biome that does not exist or is defined incorrectly, breaking generation.
What does this error mean?
World generation maps regions to biomes via a biome source. 'Failed to load biome' means a referenced biome is missing or malformed, usually introduced by a custom worldgen datapack or mod, so the dimension cannot generate.
Failed to load biome
Most Common Causes
- A datapack referencing a non-existent biome id.
- Malformed biome JSON in a worldgen datapack.
- A worldgen mod removed while its biomes are still referenced.
- A version mismatch in biome format.
- A missing namespace for a custom biome.
How To Diagnose
- Read the log for the biome id/namespace it failed on.
- Find the datapack or mod that defines (or should define) it.
- Validate the biome JSON files.
- Check whether a removed mod left dangling biome references.
Recommended Fixes
- Restore the biome source
Reinstall the mod/datapack that defines the missing biome, or fix its JSON. - Remove dangling references
If a mod was removed, clear references to its biomes from worldgen settings. - Match the format
Use biome definitions valid for your Minecraft version. - Restore from backup
Roll back to before the broken worldgen change.
Frequently Asked Questions
Removing it after generation can leave dangling biome/dimension references, plan migrations carefully.
In datapacks under data/<namespace>/worldgen/biome/.
Mostly new generation. Existing chunks may still load, but new areas referencing the biome fail.