--- a/net/minecraft/world/level/levelgen/GeneratorSettings.java
+++ b/net/minecraft/world/level/levelgen/GeneratorSettings.java
@@ -34,9 +34,14 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+// CraftBukkit start
+import net.minecraft.resources.RegistryReadOps;
+import net.minecraft.server.packs.resources.IResourceManager;
+// CraftBukkit end
+
 public class GeneratorSettings {
 
-    public static final Codec<GeneratorSettings> a = RecordCodecBuilder.create((instance) -> {
+    public static final Codec<GeneratorSettings> a = RecordCodecBuilder.<GeneratorSettings>create((instance) -> { // CraftBukkit - decompile error
         return instance.group(Codec.LONG.fieldOf("seed").stable().forGetter(GeneratorSettings::getSeed), Codec.BOOL.fieldOf("generate_features").orElse(true).stable().forGetter(GeneratorSettings::shouldGenerateMapFeatures), Codec.BOOL.fieldOf("bonus_chest").orElse(false).stable().forGetter(GeneratorSettings::c), RegistryMaterials.b(IRegistry.M, Lifecycle.stable(), WorldDimension.a).xmap(WorldDimension::a, Function.identity()).fieldOf("dimensions").forGetter(GeneratorSettings::d), Codec.STRING.optionalFieldOf("legacy_custom_options").stable().forGetter((generatorsettings) -> {
             return generatorsettings.g;
         })).apply(instance, instance.stable(GeneratorSettings::new));
@@ -120,7 +125,7 @@
     public static RegistryMaterials<WorldDimension> a(RegistryMaterials<WorldDimension> registrymaterials, Supplier<DimensionManager> supplier, ChunkGenerator chunkgenerator) {
         RegistryMaterials<WorldDimension> registrymaterials1 = new RegistryMaterials<>(IRegistry.M, Lifecycle.experimental());
 
-        registrymaterials1.a(WorldDimension.OVERWORLD, (Object) (new WorldDimension(supplier, chunkgenerator)), Lifecycle.stable());
+        registrymaterials1.a(WorldDimension.OVERWORLD, (new WorldDimension(supplier, chunkgenerator)), Lifecycle.stable()); // CraftBukkit - decompile error
         Iterator iterator = registrymaterials.d().iterator();
 
         while (iterator.hasNext()) {
@@ -229,7 +234,7 @@
         switch (b0) {
             case 0:
                 JsonObject jsonobject = !s.isEmpty() ? ChatDeserializer.a(s) : new JsonObject();
-                Dynamic<JsonElement> dynamic = new Dynamic(JsonOps.INSTANCE, jsonobject);
+                Dynamic<JsonElement> dynamic = new Dynamic(RegistryReadOps.a(JsonOps.INSTANCE, IResourceManager.Empty.INSTANCE, (IRegistryCustom.Dimension) iregistrycustom), jsonobject); // CraftBukkit - SPIGOT-6237
                 DataResult dataresult = GeneratorSettingsFlat.a.parse(dynamic);
                 Logger logger = GeneratorSettings.LOGGER;