How to Configure Better Compatibility Checker as a Modpack Author

Finding and Editing the Config File

Better Compatibility Checker reads the modpack identity from a config file that you, the pack author, control. On Forge, this file is bcc-common.toml; on Fabric, it is bcc.json. You will find it inside your instance's config folder after the mod has run at least once, or you can create it manually before shipping your pack.

Open the file in any plain text editor. You need to set two things: the modpack name and the modpack version. These are free-text fields — the mod does not validate them against CurseForge or Modrinth, so whatever string you type is what clients will compare against. Keep them short and consistent, because a single typo means every client sees a mismatch.

Matching Server and Client Values

For the check to pass, the server and every client must have identical values in both fields. The usual workflow is to edit the config once, then bundle that exact file into both your server pack and your client pack. If you update the pack version, bump the version string in both places at the same time.

If the mod is missing from the server entirely, clients fall back to the vanilla Forge compatibility screen, so the custom green checkmark will not appear. Always confirm the mod is present on both sides before troubleshooting a red X.