Using Biome Replacer With Datapack or Modded Biomes

Get the Correct Biome IDs

Datapack and modded biomes use namespaced IDs that differ from vanilla. Find them in the datapack's biome JSON files or by checking the F3 screen while standing in the biome. The namespace is whatever the datapack or mod uses, followed by the biome name.

Write Rules With Full IDs

In biome-replacer.properties, always use the complete namespaced ID on both sides of the >. For example, a custom biome might look like yourpack:custom_forest > minecraft:forest. Mixing a custom biome on the left with a vanilla biome on the right is fine, and so is the reverse. This makes the mod useful for tweaking datapack-based generators where a biome generates too often or in the wrong place.

Load Order and Testing

Restart the server after editing so both the datapack and the mod config are active. Generate fresh chunks and confirm the swap on the F3 screen. If a custom biome fails to replace, the most common cause is a typo in the namespace or a biome that the datapack registers under a different ID than expected. Since the mod is server-side only, clients do not need matching config, but they do need the datapack or mod that defines the biome to be present.