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Frequently Asked Questions

General​

What Minecraft / NeoForge versions does RegistryLib support?​

RegistryLib targets NeoForge 26.1 on Minecraft 1.21+. Check the GitHub releases page for the exact version matrix.

Is RegistryLib a fork of Registrate?​

RegistryLib is inspired by Registrate but is a clean-room rebuild for modern NeoForge. It shares the fluent-API philosophy but differs in implementation, type hierarchy, and feature set. See What is RegistryLib? for a detailed comparison.

Can I use RegistryLib alongside vanilla registration?​

Yes. RegistryLib does not replace the NeoForge registry system; it wraps it. You can mix RegistryLib chains with DeferredRegister calls in the same mod without conflict.

Setup​

Gradle cannot resolve the RegistryLib dependency​

  1. Ensure your settings.gradle or build.gradle includes the Gtodyssey Maven repository: https://maven.gtodyssey.com/releases.
  2. Check your network can reach maven.gtodyssey.com.
  3. Run ./gradlew build --refresh-dependencies to clear cached resolution failures.

See Installation & Setup for the full walkthrough.

runData or runClient fails at startup​

  • Confirm your NeoForge and Minecraft versions align with the RegistryLib release you are using.
  • Make sure the class that initializes RegistryCore.create(MOD_ID) is loaded during mod construction, such as from your @Mod class.

Registration​

I called .register() but the item does not appear in-game​

  1. Class not loaded: the field holding your ItemEntry must be in a class that is referenced during mod construction. A static field in an unreferenced class is never initialized.
  2. Missing creative tab: call .addDefaultTab() or .addTab(...) to place it in a creative tab.
  3. Missing model/texture: call .defaultModel(), or provide a texture via .texture(...) or a resource pack.

I used to get a NullPointerException from .get() but now I see an IllegalStateException​

This is intentional. Entry .get() now throws IllegalStateException with a descriptive message instead of a raw NPE. The fix is the same: do not call .get() before registration completes. If you need a safe check, use isBound() or getOptional(). See Troubleshooting for details.

What is the difference between item() and componentItem()?​

item() creates a plain Item. componentItem() creates a ComponentItem or IComponentItem implementation that supports the attachment system for modular behavior composition. Use componentItem() when you need .attach(...).

Can I register entries conditionally?​

RegistryLib builders are submitted at .register() time. You can conditionally skip chains with normal Java control flow. However, once .register() is called, the entry is registered unconditionally; there is no built-in config-gated registration.

Datagen​

My language file is missing entries​

  • Ensure .lang("Display Name") is present on each chain, or use .defaultLang().
  • Run ./gradlew runData after any lang change. RegistryLib generates lang files during datagen, not at runtime.

How do I add recipes?​

Use addRecipeData(...) on your builder chain or on RegistryCore. See Recipes and Tags.

Still stuck?​

Check the Troubleshooting page for error-specific solutions, or open an issue on GitHub.