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Troubleshooting

Build & Dependency Errors​

Could not resolve com.gto:registrylib:x.x.x​

Cause: Gradle cannot reach the Maven repository.

Fix:

  1. Ensure your settings.gradle or build.gradle includes the Gtodyssey Maven repository.
  2. Verify the URL is https://maven.gtodyssey.com/releases.
  3. Check your network connectivity to maven.gtodyssey.com.

NoClassDefFoundError or ClassNotFoundException for RegistryLib classes​

Cause: RegistryLib is not on the runtime classpath.

Fix: Ensure you are using implementation (not compileOnly) in your build.gradle dependencies:

dependencies {
    implementation 'com.gto:registrylib:7.0.8'
}

Registration Errors​

Entry exists in code but does not appear in-game​

Cause: The class containing the static final entry field was never loaded.

Fix: Reference the class from your @Mod constructor or another class that is guaranteed to load:

@Mod("mymod")
public class MyMod {
    public MyMod(IEventBus bus) {
        MyItems.init(); // force class loading
    }
}

NullPointerException when calling .get() on an Entry​

Cause: .get() was called before registration is complete (before FMLCommonSetupEvent).

Fix: Use the Entry as a Holder or Supplier where possible, or defer the .get() call to an event handler that runs after registration.

.attach(...) compilation error on plain Item​

Cause: Attachments are only supported on ComponentItem or IComponentItem implementations.

Fix: Switch from .item(...) to .componentItem(...).

IllegalStateException: Builder already registered: <name>​

Cause: .register() or .build() was called more than once on the same builder instance. Each builder is single-use.

Fix: Ensure each builder chain calls .register() exactly once. If you need two entries with similar configuration, create two separate chains.

Datagen Errors​

runData produces no output files​

Cause: Registration chains were not executed before datagen runs.

Fix: Ensure your entry-holding classes are loaded during mod construction, before the GatherDataEvent fires.

Generated lang file is missing some entries​

Cause: .lang(...) or .defaultLang() was not called on those chains.

Fix: Add .lang("Display Name") to every registration chain that needs a display name.

Runtime Errors​

IllegalStateException: Renderer class loaded on server​

Cause: A BlockEntityRenderer or client-only class was referenced eagerly on the dedicated server.

Fix: Use lazy loading for renderer registration:

.renderer(() -> MyBlockEntityRenderer::new)

The Supplier wrapping ensures the renderer class is only loaded on the client. See Performance & Optimization.

Tooltip box renders at the wrong position​

Cause: A custom SubNode implementation returns incorrect getWidth() or getHeight().

Fix: Ensure your node's size methods return accurate pixel dimensions. See Tooltip System.

Still stuck?​

Check the FAQ or open an issue on GitHub.