diff --git a/core/src/main/java/github/nighter/smartspawner/extras/HopperHandler.java b/core/src/main/java/github/nighter/smartspawner/extras/HopperHandler.java
index 9c99780d..0607f0ed 100644
--- a/core/src/main/java/github/nighter/smartspawner/extras/HopperHandler.java
+++ b/core/src/main/java/github/nighter/smartspawner/extras/HopperHandler.java
@@ -180,6 +180,30 @@ public void stopHopperTask(Location hopperLoc) {
         }
     }
 
+    /**
+     * Restart hopper task for a spawner location.
+     * This is called when spawner stack size changes to ensure hopper continues working.
+     * @param spawnerLoc The location of the spawner
+     */
+    public void restartHopperForSpawner(Location spawnerLoc) {
+        if (!plugin.getConfig().getBoolean("hopper.enabled", false)) return;
+        
+        // Find hopper below the spawner
+        Block spawnerBlock = spawnerLoc.getBlock();
+        if (spawnerBlock.getType() != Material.SPAWNER) return;
+        
+        Block hopperBlock = spawnerBlock.getRelative(BlockFace.DOWN);
+        if (hopperBlock.getType() != Material.HOPPER) return;
+        
+        Location hopperLoc = hopperBlock.getLocation();
+        
+        // Stop existing hopper task if any
+        stopHopperTask(hopperLoc);
+        
+        // Start new hopper task
+        startHopperTask(hopperLoc, spawnerLoc);
+    }
+
     private void transferItems(Location hopperLoc, Location spawnerLoc) {
         SpawnerData spawner = spawnerManager.getSpawnerByLocation(spawnerLoc);
         if (spawner == null) return;
diff --git a/core/src/main/java/github/nighter/smartspawner/spawner/gui/main/SpawnerMenuAction.java b/core/src/main/java/github/nighter/smartspawner/spawner/gui/main/SpawnerMenuAction.java
index 5d258eb9..f98800d1 100644
--- a/core/src/main/java/github/nighter/smartspawner/spawner/gui/main/SpawnerMenuAction.java
+++ b/core/src/main/java/github/nighter/smartspawner/spawner/gui/main/SpawnerMenuAction.java
@@ -10,7 +10,6 @@
 import github.nighter.smartspawner.spawner.gui.synchronization.SpawnerGuiViewManager;
 import github.nighter.smartspawner.spawner.properties.SpawnerData;
 import github.nighter.smartspawner.spawner.sell.SpawnerSellManager;
-import github.nighter.smartspawner.utils.DynamicMaterialDetector;
 import org.bukkit.Bukkit;
 import org.bukkit.Material;
 import org.bukkit.Particle;
@@ -32,8 +31,18 @@
 import java.util.concurrent.ConcurrentHashMap;
 
 public class SpawnerMenuAction implements Listener {
-    private static final Set<Material> SPAWNER_INFO_MATERIALS = 
-        DynamicMaterialDetector.getSpawnerInfoMaterials();
+    // Spawner info materials - manually defined to avoid Material.values() iteration
+    // which can trigger CraftLegacy initialization
+    private static final Set<Material> SPAWNER_INFO_MATERIALS = Set.of(
+        Material.PLAYER_HEAD,
+        Material.SPAWNER,
+        Material.ZOMBIE_HEAD,
+        Material.SKELETON_SKULL,
+        Material.WITHER_SKELETON_SKULL,
+        Material.CREEPER_HEAD,
+        Material.PIGLIN_HEAD,
+        Material.DRAGON_HEAD
+    );
     private final SmartSpawner plugin;
     private final SpawnerMenuUI spawnerMenuUI;
     private final SpawnerStackerUI spawnerStackerUI;
diff --git a/core/src/main/java/github/nighter/smartspawner/spawner/loot/EntityLootRegistry.java b/core/src/main/java/github/nighter/smartspawner/spawner/loot/EntityLootRegistry.java
index 45d7f8b0..a4bd4f1e 100644
--- a/core/src/main/java/github/nighter/smartspawner/spawner/loot/EntityLootRegistry.java
+++ b/core/src/main/java/github/nighter/smartspawner/spawner/loot/EntityLootRegistry.java
@@ -54,6 +54,16 @@ public void loadConfigurations() {
                 continue;
             }
 
+            // Validate entity type exists in current version
+            EntityType entityType;
+            try {
+                entityType = EntityType.valueOf(entityName.toUpperCase());
+            } catch (IllegalArgumentException e) {
+                plugin.getLogger().warning("Entity type '" + entityName + "' is not available in server version " +
+                        plugin.getServer().getBukkitVersion() + " - skipping");
+                continue;
+            }
+
             ConfigurationSection entitySection = lootConfig.getConfigurationSection(entityName);
             if (entitySection == null) continue;
 
diff --git a/core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java b/core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java
index fdf192fe..b206b5c1 100644
--- a/core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java
+++ b/core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java
@@ -243,6 +243,12 @@ private void updateStackSize(int newStackSize) {
         if (plugin.getSpawnerMenuFormUI() != null) {
             plugin.getSpawnerMenuFormUI().invalidateSpawnerCache(this.spawnerId);
         }
+
+        // Restart hopper task if hopper integration is enabled
+        // This ensures hopper continues to work after stack size changes
+        if (plugin.getHopperHandler() != null) {
+            plugin.getHopperHandler().restartHopperForSpawner(this.spawnerLocation);
+        }
     }
 
     private void recreateVirtualInventory() {
diff --git a/core/src/main/java/github/nighter/smartspawner/utils/DynamicMaterialDetector.java b/core/src/main/java/github/nighter/smartspawner/utils/DynamicMaterialDetector.java
deleted file mode 100644
index b0b80d79..00000000
--- a/core/src/main/java/github/nighter/smartspawner/utils/DynamicMaterialDetector.java
+++ /dev/null
@@ -1,51 +0,0 @@
-package github.nighter.smartspawner.utils;
-
-import org.bukkit.Material;
-
-import java.util.Arrays;
-import java.util.Set;
-import java.util.stream.Collectors;
-
-/**
- * Dynamically detects valid materials for spawner GUI based on current Minecraft version.
- * Supports automatic detection of:
- * - Player heads
- * - Mob skulls/heads
- * - Spawner blocks
- */
-public class DynamicMaterialDetector {
-    private static final Set<Material> SPAWNER_INFO_MATERIALS;
-    
-    static {
-        // Auto-detect all head/skull materials from current version
-        SPAWNER_INFO_MATERIALS = Arrays.stream(Material.values())
-            .filter(material -> {
-                String name = material.name();
-                return name.equals("PLAYER_HEAD") ||
-                       name.equals("SPAWNER") ||
-                       name.endsWith("_HEAD") ||
-                       name.endsWith("_SKULL");
-            })
-            .filter(Material::isItem)
-            .collect(Collectors.toUnmodifiableSet());
-    }
-    
-    /**
-     * Get all valid spawner info materials for the current Minecraft version
-     * 
-     * @return Unmodifiable set of spawner info materials
-     */
-    public static Set<Material> getSpawnerInfoMaterials() {
-        return SPAWNER_INFO_MATERIALS;
-    }
-    
-    /**
-     * Check if a material is a valid spawner info material
-     * 
-     * @param material Material to check
-     * @return true if the material is a valid spawner info material
-     */
-    public static boolean isValidSpawnerInfoMaterial(Material material) {
-        return SPAWNER_INFO_MATERIALS.contains(material);
-    }
-}