Index: src/main/java/net/minecraft/server/CommandDispatcher.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/main/java/net/minecraft/server/CommandDispatcher.java b/src/main/java/net/minecraft/server/CommandDispatcher.java
--- a/src/main/java/net/minecraft/server/CommandDispatcher.java	(revision 2092b553cf3dbfc5fbe5534ac1bfd42e2c90a9fc)
+++ b/src/main/java/net/minecraft/server/CommandDispatcher.java	(date 1609100118789)
@@ -35,7 +35,6 @@
     // CraftBukkit start
     public final CommandDispatcher init(boolean flag) {
         CommandAdvancement.a(this.b);
-        CommandExecute.a(this.b);
         CommandBossBar.a(this.b);
         CommandClear.a(this.b);
         CommandClone.a(this.b);
@@ -48,7 +47,6 @@
         CommandMe.a(this.b);
         CommandEnchant.a(this.b);
         CommandXp.a(this.b);
-        CommandFill.a(this.b);
         CommandForceload.a(this.b);
         CommandFunction.a(this.b);
         CommandGamemode.a(this.b);
Index: src/main/java/net/minecraft/server/MinecraftServer.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
--- a/src/main/java/net/minecraft/server/MinecraftServer.java	(revision 2092b553cf3dbfc5fbe5534ac1bfd42e2c90a9fc)
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java	(date 1609100120517)
@@ -175,11 +175,18 @@
     public final SlackActivityAccountant slackActivityAccountant = new SlackActivityAccountant();
     // Spigot end
 
+    protected static Thread dispenserRegistryInit;
+
     public MinecraftServer(OptionSet options, Proxy proxy, DataFixer datafixer, CommandDispatcher commanddispatcher, YggdrasilAuthenticationService yggdrasilauthenticationservice, MinecraftSessionService minecraftsessionservice, GameProfileRepository gameprofilerepository, UserCache usercache, WorldLoadListenerFactory worldloadlistenerfactory, String s) {
         super("Server");
         this.ae = new ResourceManager(EnumResourcePackType.SERVER_DATA, this.serverThread);
         this.resourcePackRepository = new ResourcePackRepository<>(ResourcePackLoader::new);
         this.craftingManager = new CraftingManager();
+        try {
+            dispenserRegistryInit.join();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
         this.tagRegistry = new TagRegistry();
         this.scoreboardServer = new ScoreboardServer(this);
         this.bossBattleCustomData = new BossBattleCustomData(this);
@@ -1185,8 +1192,12 @@
             }
 
             CrashReport.h();
-            DispenserRegistry.init();
-            DispenserRegistry.c();
+            dispenserRegistryInit = new Thread(() -> {
+                DispenserRegistry.init();
+                DispenserRegistry.c();
+            });
+            dispenserRegistryInit.start();
+
             File s = (File) optionset.valueOf("universe"); // CraftBukkit
             YggdrasilAuthenticationService yggdrasilauthenticationservice = new YggdrasilAuthenticationService(Proxy.NO_PROXY, UUID.randomUUID().toString());
             MinecraftSessionService minecraftsessionservice = yggdrasilauthenticationservice.createMinecraftSessionService();