diff --git a/core/src/main/java/org/geysermc/geyser/command/CommandRegistry.java b/core/src/main/java/org/geysermc/geyser/command/CommandRegistry.java
index 03569d49f..9de7582a5 100644
--- a/core/src/main/java/org/geysermc/geyser/command/CommandRegistry.java
+++ b/core/src/main/java/org/geysermc/geyser/command/CommandRegistry.java
@@ -320,13 +320,17 @@ public class CommandRegistry implements EventRegistrar {
         cloud.commandExecutor().executeCommand(source, command);
     }
 
-    public void export(GeyserSession session, List<CommandData> bedrockCommands) {
+    public void export(GeyserSession session, List<CommandData> bedrockCommands, Set<String> knownAliases) {
         cloud.commandTree().rootNodes().forEach(commandTree -> {
             var command = commandTree.command();
             // Command null happens if you register an extension command with custom Cloud parameters...
             if (command == null || session.hasPermission(command.commandPermission().permissionString())) {
                 var rootComponent = commandTree.component();
                 String name = rootComponent.name();
+                if (!knownAliases.add(name)) {
+                    // If the server already defined the command, let's not crash.
+                    return;
+                }
 
                 LinkedHashMap<String, Set<CommandEnumConstraint>> values = new LinkedHashMap<>();
                 for (String s : rootComponent.aliases()) {
diff --git a/core/src/main/java/org/geysermc/geyser/registry/populator/BlockRegistryPopulator.java b/core/src/main/java/org/geysermc/geyser/registry/populator/BlockRegistryPopulator.java
index a8c3ee89f..b95da4f8f 100644
--- a/core/src/main/java/org/geysermc/geyser/registry/populator/BlockRegistryPopulator.java
+++ b/core/src/main/java/org/geysermc/geyser/registry/populator/BlockRegistryPopulator.java
@@ -283,7 +283,7 @@ public final class BlockRegistryPopulator {
                         .build();
                 }
 
-                GeyserBedrockBlock vanillaBedrockDefinition = blockStateOrderedMap.getOrDefault(bedrockTag, airDefinition); // FIXME EEE
+                GeyserBedrockBlock vanillaBedrockDefinition = blockStateOrderedMap.get(bedrockTag);
 
                 GeyserBedrockBlock bedrockDefinition;
                 CustomBlockState blockStateOverride = BlockRegistries.CUSTOM_BLOCK_STATE_OVERRIDES.get(javaRuntimeId);
diff --git a/core/src/main/java/org/geysermc/geyser/registry/populator/ItemRegistryPopulator.java b/core/src/main/java/org/geysermc/geyser/registry/populator/ItemRegistryPopulator.java
index e8b894759..18a34f088 100644
--- a/core/src/main/java/org/geysermc/geyser/registry/populator/ItemRegistryPopulator.java
+++ b/core/src/main/java/org/geysermc/geyser/registry/populator/ItemRegistryPopulator.java
@@ -84,6 +84,7 @@ import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -95,7 +96,7 @@ import java.util.concurrent.atomic.AtomicInteger;
  */
 public class ItemRegistryPopulator {
 
-    record PaletteVersion(String version, int protocolVersion, Map<Item, String> javaOnlyItems, Remapper remapper) {
+    record PaletteVersion(String version, int protocolVersion, Map<Item, Item> javaOnlyItems, Remapper remapper) {
 
         public PaletteVersion(String version, int protocolVersion) {
             this(version, protocolVersion, Collections.emptyMap(), (item, mapping) -> mapping);
@@ -109,11 +110,17 @@ public class ItemRegistryPopulator {
     }
 
     public static void populate() {
+        List<Item> bundles = List.of(Items.BUNDLE, Items.BLACK_BUNDLE, Items.BLUE_BUNDLE, Items.BROWN_BUNDLE, Items.CYAN_BUNDLE, Items.GRAY_BUNDLE,
+            Items.GREEN_BUNDLE, Items.LIGHT_BLUE_BUNDLE, Items.LIGHT_GRAY_BUNDLE, Items.LIME_BUNDLE, Items.MAGENTA_BUNDLE, Items.ORANGE_BUNDLE, Items.RED_BUNDLE,
+            Items.PINK_BUNDLE, Items.PURPLE_BUNDLE, Items.WHITE_BUNDLE, Items.YELLOW_BUNDLE);
+        Map<Item, Item> pre1_21_2Items = new HashMap<>();
+        bundles.forEach(bundle -> pre1_21_2Items.put(bundle, Items.SHULKER_SHELL));
+
         List<PaletteVersion> paletteVersions = new ArrayList<>(3);
-        paletteVersions.add(new PaletteVersion("1_20_80", Bedrock_v671.CODEC.getProtocolVersion(), Collections.emptyMap(), Conversion685_671::remapItem));
-        paletteVersions.add(new PaletteVersion("1_21_0", Bedrock_v685.CODEC.getProtocolVersion(), Collections.emptyMap(), Conversion712_685::remapItem));
-        paletteVersions.add(new PaletteVersion("1_21_20", Bedrock_v712.CODEC.getProtocolVersion(), Collections.emptyMap(), Conversion729_712::remapItem));
-        paletteVersions.add(new PaletteVersion("1_21_30", Bedrock_v729.CODEC.getProtocolVersion(), Collections.emptyMap(), Conversion748_729::remapItem));
+        paletteVersions.add(new PaletteVersion("1_20_80", Bedrock_v671.CODEC.getProtocolVersion(), pre1_21_2Items, Conversion685_671::remapItem));
+        paletteVersions.add(new PaletteVersion("1_21_0", Bedrock_v685.CODEC.getProtocolVersion(), pre1_21_2Items, Conversion712_685::remapItem));
+        paletteVersions.add(new PaletteVersion("1_21_20", Bedrock_v712.CODEC.getProtocolVersion(), pre1_21_2Items, Conversion729_712::remapItem));
+        paletteVersions.add(new PaletteVersion("1_21_30", Bedrock_v729.CODEC.getProtocolVersion(), pre1_21_2Items, Conversion748_729::remapItem));
         paletteVersions.add(new PaletteVersion("1_21_40", Bedrock_v748.CODEC.getProtocolVersion()));
 
         GeyserBootstrap bootstrap = GeyserImpl.getInstance().getBootstrap();
@@ -227,7 +234,7 @@ public class ItemRegistryPopulator {
 
             Set<Item> javaOnlyItems = new ObjectOpenHashSet<>();
             Collections.addAll(javaOnlyItems, Items.SPECTRAL_ARROW, Items.DEBUG_STICK,
-                    Items.KNOWLEDGE_BOOK, Items.TIPPED_ARROW, Items.BUNDLE);
+                    Items.KNOWLEDGE_BOOK, Items.TIPPED_ARROW);
             if (!customItemsAllowed) {
                 javaOnlyItems.add(Items.FURNACE_MINECART);
             }
@@ -243,9 +250,9 @@ public class ItemRegistryPopulator {
                     throw new RuntimeException("Extra item in mappings? " + entry.getKey());
                 }
                 GeyserMappingItem mappingItem;
-                String replacementItem = palette.javaOnlyItems().get(javaItem);
+                Item replacementItem = palette.javaOnlyItems().get(javaItem);
                 if (replacementItem != null) {
-                    mappingItem = items.get(replacementItem); // java only item, a java id fallback has been provided
+                    mappingItem = items.get(replacementItem.javaIdentifier()); // java only item, a java id fallback has been provided
                 } else {
                     // check if any mapping changes need to be made on this version
                     mappingItem = palette.remapper().remap(javaItem, entry.getValue());
@@ -260,8 +267,7 @@ public class ItemRegistryPopulator {
                 String bedrockIdentifier = mappingItem.getBedrockIdentifier();
                 ItemDefinition definition = definitions.get(bedrockIdentifier);
                 if (definition == null) {
-                    definition = definitions.get("minecraft:air");
-                    //throw new RuntimeException("Missing Bedrock ItemDefinition in version " + palette.version() + " for mapping: " + mappingItem);
+                    throw new RuntimeException("Missing Bedrock ItemDefinition in version " + palette.version() + " for mapping: " + mappingItem);
                 }
 
                 BlockDefinition bedrockBlock = null;
diff --git a/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaCommandsTranslator.java b/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaCommandsTranslator.java
index 8eff3d16c..5500deb80 100644
--- a/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaCommandsTranslator.java
+++ b/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaCommandsTranslator.java
@@ -215,7 +215,7 @@ public class JavaCommandsTranslator extends PacketTranslator<ClientboundCommands
         }
 
         if (session.getGeyser().platformType() == PlatformType.STANDALONE) {
-            session.getGeyser().commandRegistry().export(session, commandData);
+            session.getGeyser().commandRegistry().export(session, commandData, knownAliases);
         }
 
         // Add our commands to the AvailableCommandsPacket for the bedrock client
diff --git a/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaRecipeBookAddTranslator.java b/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaRecipeBookAddTranslator.java
index 5cc2e3063..d59d608a2 100644
--- a/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaRecipeBookAddTranslator.java
+++ b/core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaRecipeBookAddTranslator.java
@@ -110,6 +110,9 @@ public class JavaRecipeBookAddTranslator extends PacketTranslator<ClientboundRec
                     for (int i = 0; i < left.size(); i++) {
                         List<ItemDescriptorWithCount> inputs = left.get(i);
                         String recipeId = contents.id() + "_" + i;
+                        if (recipeId.equals("1318_0")) {
+                            System.out.println(display);
+                        }
                         int recipeNetworkId = netId++;
                         craftingDataPacket.getCraftingData().add(ShapedRecipeData.shaped(recipeId,
                             shapedRecipe.width(), shapedRecipe.height(), inputs,
@@ -268,8 +271,12 @@ public class JavaRecipeBookAddTranslator extends PacketTranslator<ClientboundRec
         Pair<Item, ItemData> pair = translateToOutput(session, display.result());
         if (pair == null || !pair.right().isValid()) {
             // Likely modded item Bedrock will complain about
+            // Implementation note: ItemData#isValid() may return true for air because count might be > 0 and the air definition may not be ItemDefinition.AIR
             return null;
         }
+        if (pair.left() == Items.PALE_OAK_TRAPDOOR) {
+            System.out.println(pair.right());
+        }
 
         ItemData output = pair.right();
         if (!(pair.left() instanceof BedrockRequiresTagItem)) {
diff --git a/core/src/main/resources/mappings b/core/src/main/resources/mappings
index 4200a8c57..e1eafe2c5 160000
--- a/core/src/main/resources/mappings
+++ b/core/src/main/resources/mappings
@@ -1 +1 @@
-Subproject commit 4200a8c57a79a87b5b9e7ea1aaf9d5522c4f5626
+Subproject commit e1eafe2c5304012d23acba80659459f7868fe2b1