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Minecraft 1.19.3 -> 1.19.4 Forge Mod Migration Primer

This is a high level, non-exhaustive overview on how to migrate your mod from 1.19.3 to 1.19.4 using Forge. All provided names use the official mojang mappings.

This primer is licensed under the Creative Commons Attribution 4.0 International, so feel free to use it as a reference and leave a link so that other readers can consume the primer.

If there's any incorrect or missing information, please file an issue on this repository or ping @ChampionAsh5357 in the Neoforged Discord server.

Vanilla Changes​

Vanilla changes are listed here.

Creative Tabs​

Custom creative tabs from the previous primer are now slightly modified to take in the two parameters:

// Registered on the MOD event bus
// Assume we have RegistryObject<Item> and RegistryObject<Block> called ITEM and BLOCK
@SubscribeEvent
public void buildContents(CreativeModeTabEvent.Register event) {
  event.registerCreativeModeTab(new ResourceLocation(MOD_ID, "example"), builder ->
    // Set name of tab to display
    builder.title(Component.translatable("item_group." + MOD_ID + ".example"))
    // Set icon of creative tab
    .icon(() -> new ItemStack(ITEM.get()))
    // Add default items to tab
    .displayItems((params, output) -> {
      output.accept(ITEM.get());
      output.accept(BLOCK.get());
    })
  );
}

Additionally, net.minecraftforge.event.CreativeModeTabEvent$BuildContents can access the parameters via #getParameters. The other methods now delegate to the parameters for better compatibility when updating from 1.19.3.

Spawn Events Refactor​

As of 45.0.23, spawn events have been completely refactored. For starters, LivingSpawnEvent has been renamed to MobSpawnEvent. Even further CheckSpawn and SpecialSpawn hae been merged into a single event: FinalizeSpawn. FinalizeSpawn can be canceled to prevent Mob#finalizeSpawn from being called while the entity itself can be prevent using FinalizeSpawn#setSpawnCancelled.

If you want to learn more about this event and the technical changes, see the blog post.

New Registries​

Forge has added a new static registry for ItemDisplayContexts aptly named forge:display_contexts for registering perspectives an item may be rendered within, replacing custom TransformTypes. There can only be at most 256 display contexts.

Sprite Registration Refactoring​

As of 45.0.25, all net.minecraftforge.client.event.RegisterParticleProvidersEvent#register methods have been deprecated for removal, opting to switch to method names which better specify their usecase:

  • #register(ParticleType, ParticleProvider) -> #registerSpecial
  • #register(ParticleType, ParticleProvider$Sprite) -> #registerSprite
  • #register(ParticleType, ParticleEngine$SpriteParticleRegistration) -> #registerSpriteSet

Minor Changes​

  • net.minecraftforge.fml.CrashReportCallables can now be supplied a callable which will append to the system report when the boolean supplier returns true.