--- a/net/minecraft/server/ServerAdvancementManager.java
+++ b/net/minecraft/server/ServerAdvancementManager.java
@@ -22,7 +_,7 @@
 
 public class ServerAdvancementManager extends SimpleJsonResourceReloadListener<Advancement> {
     private static final Logger LOGGER = LogUtils.getLogger();
-    public Map<ResourceLocation, AdvancementHolder> advancements = Map.of();
+    public Map<ResourceLocation, AdvancementHolder> advancements = new java.util.HashMap<>(); // CraftBukkit - SPIGOT-7734: mutable
     private AdvancementTree tree = new AdvancementTree();
     private final HolderLookup.Provider registries;
 
@@ -35,12 +_,18 @@
     protected void apply(Map<ResourceLocation, Advancement> object, ResourceManager resourceManager, ProfilerFiller profiler) {
         Builder<ResourceLocation, AdvancementHolder> builder = ImmutableMap.builder();
         object.forEach((resourceLocation, advancement) -> {
+            // Spigot start
+            if (org.spigotmc.SpigotConfig.disabledAdvancements != null && (org.spigotmc.SpigotConfig.disabledAdvancements.contains("*") || org.spigotmc.SpigotConfig.disabledAdvancements.contains(resourceLocation.toString()) || org.spigotmc.SpigotConfig.disabledAdvancements.contains(resourceLocation.getNamespace()))) {
+                return;
+            }
+            // Spigot end
             this.validate(resourceLocation, advancement);
             builder.put(resourceLocation, new AdvancementHolder(resourceLocation, advancement));
         });
-        this.advancements = builder.buildOrThrow();
+        this.advancements = new java.util.HashMap<>(builder.buildOrThrow()); // CraftBukkit - SPIGOT-7734: mutable
         AdvancementTree advancementTree = new AdvancementTree();
         advancementTree.addAll(this.advancements.values());
+        LOGGER.info("Loaded {} advancements", advancementTree.nodes().size()); // Paper - Improve logging and errors; moved from AdvancementTree#addAll
 
         for (AdvancementNode advancementNode : advancementTree.roots()) {
             if (advancementNode.holder().value().display().isPresent()) {