diff --git a/common/src/main/java/com/viaversion/viabackwards/api/data/BackwardsMappingData.java b/common/src/main/java/com/viaversion/viabackwards/api/data/BackwardsMappingData.java
index a1acfe5e..86ce4e85 100644
--- a/common/src/main/java/com/viaversion/viabackwards/api/data/BackwardsMappingData.java
+++ b/common/src/main/java/com/viaversion/viabackwards/api/data/BackwardsMappingData.java
@@ -55,7 +55,7 @@ public class BackwardsMappingData extends MappingDataBase {
 
     public BackwardsMappingData(final String unmappedVersion, final String mappedVersion, @Nullable final Class<? extends Protocol<?, ?, ?, ?>> vvProtocolClass) {
         super(unmappedVersion, mappedVersion);
-        Preconditions.checkArgument(vvProtocolClass == null || !vvProtocolClass.isAssignableFrom(BackwardsProtocol.class));
+        Preconditions.checkArgument(vvProtocolClass == null || !BackwardsProtocol.class.isAssignableFrom(vvProtocolClass));
         this.vvProtocolClass = vvProtocolClass;
     }
 
diff --git a/common/src/main/java/com/viaversion/viabackwards/api/rewriters/TranslatableRewriter.java b/common/src/main/java/com/viaversion/viabackwards/api/rewriters/TranslatableRewriter.java
index 910f333b..9e94723d 100644
--- a/common/src/main/java/com/viaversion/viabackwards/api/rewriters/TranslatableRewriter.java
+++ b/common/src/main/java/com/viaversion/viabackwards/api/rewriters/TranslatableRewriter.java
@@ -17,14 +17,14 @@
  */
 package com.viaversion.viabackwards.api.rewriters;
 
+import com.viaversion.nbt.tag.CompoundTag;
+import com.viaversion.nbt.tag.StringTag;
 import com.viaversion.viabackwards.api.BackwardsProtocol;
 import com.viaversion.viabackwards.api.data.BackwardsMappingDataLoader;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.protocol.packet.ClientboundPacketType;
 import com.viaversion.viaversion.libs.gson.JsonElement;
 import com.viaversion.viaversion.libs.gson.JsonObject;
-import com.viaversion.nbt.tag.CompoundTag;
-import com.viaversion.nbt.tag.StringTag;
 import com.viaversion.viaversion.rewriter.ComponentRewriter;
 import java.util.HashMap;
 import java.util.Map;
@@ -56,11 +56,11 @@ public class TranslatableRewriter<C extends ClientboundPacketType> extends Compo
         this(protocol, type, protocol.getClass().getSimpleName().replace("Protocol", "").split("To")[0].replace("_", "."));
     }
 
-    public TranslatableRewriter(final BackwardsProtocol<C, ?, ?, ?> protocol, final ReadType type, final String sectionIdentifier) {
+    public TranslatableRewriter(final BackwardsProtocol<C, ?, ?, ?> protocol, final ReadType type, final String version) {
         super(protocol, type);
-        final Map<String, String> translatableMappings = getTranslatableMappings(sectionIdentifier);
+        final Map<String, String> translatableMappings = getTranslatableMappings(version);
         if (translatableMappings == null) {
-            protocol.getLogger().warning("Missing " + sectionIdentifier + " translatables!");
+            protocol.getLogger().warning("Missing " + version + " translatables!");
             this.translatables = new HashMap<>();
         } else {
             this.translatables = translatableMappings;
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_20_5to1_20_3/rewriter/BlockItemPacketRewriter1_20_5.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_20_5to1_20_3/rewriter/BlockItemPacketRewriter1_20_5.java
index 84e6de54..e81313bf 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_20_5to1_20_3/rewriter/BlockItemPacketRewriter1_20_5.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_20_5to1_20_3/rewriter/BlockItemPacketRewriter1_20_5.java
@@ -360,8 +360,8 @@ public final class BlockItemPacketRewriter1_20_5 extends BackwardsStructuredItem
         // Convert to structured item first
         final Item structuredItem = vvProtocol.getItemRewriter().toStructuredItem(connection, item);
 
-        item.structuredData().setIdLookup(protocol, false);
-        enchantmentRewriter.handleToServer(item);
+        structuredItem.structuredData().setIdLookup(protocol, false);
+        enchantmentRewriter.handleToServer(structuredItem);
 
         return super.handleItemToServer(connection, structuredItem);
     }
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/Protocol1_21To1_20_5.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/Protocol1_21To1_20_5.java
index 4bc13851..ab4bf6c3 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/Protocol1_21To1_20_5.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/Protocol1_21To1_20_5.java
@@ -28,6 +28,7 @@ import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.entities.EntityTypes1_20_5;
 import com.viaversion.viaversion.api.protocol.packet.provider.PacketTypesProvider;
 import com.viaversion.viaversion.api.protocol.packet.provider.SimplePacketTypesProvider;
+import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.data.entity.EntityTrackerBase;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundConfigurationPackets1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPacket1_20_5;
@@ -35,54 +36,98 @@ import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPac
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundConfigurationPackets1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundPacket1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundPackets1_20_5;
-import com.viaversion.viaversion.rewriter.AttributeRewriter;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.Protocol1_20_5To1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundConfigurationPackets1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPacket1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPackets1_21;
 import com.viaversion.viaversion.rewriter.ComponentRewriter.ReadType;
 import com.viaversion.viaversion.rewriter.StatisticsRewriter;
 import com.viaversion.viaversion.rewriter.TagRewriter;
 
 import static com.viaversion.viaversion.util.ProtocolUtil.packetTypeMap;
 
-public final class Protocol1_21To1_20_5 extends BackwardsProtocol<ClientboundPacket1_20_5, ClientboundPacket1_20_5, ServerboundPacket1_20_5, ServerboundPacket1_20_5> {
+public final class Protocol1_21To1_20_5 extends BackwardsProtocol<ClientboundPacket1_21, ClientboundPacket1_20_5, ServerboundPacket1_20_5, ServerboundPacket1_20_5> {
 
-    public static final BackwardsMappingData MAPPINGS = new BackwardsMappingData("1.21", "1.20.5", Protocol1_21To1_20_5.class);
+    public static final BackwardsMappingData MAPPINGS = new BackwardsMappingData("1.21", "1.20.5", Protocol1_20_5To1_21.class);
     private final EntityPacketRewriter1_21 entityRewriter = new EntityPacketRewriter1_21(this);
     private final BlockItemPacketRewriter1_21 itemRewriter = new BlockItemPacketRewriter1_21(this);
-    private final TranslatableRewriter<ClientboundPacket1_20_5> translatableRewriter = new TranslatableRewriter<>(this, ReadType.NBT);
-    private final TagRewriter<ClientboundPacket1_20_5> tagRewriter = new TagRewriter<>(this);
+    private final TranslatableRewriter<ClientboundPacket1_21> translatableRewriter = new TranslatableRewriter<>(this, ReadType.NBT);
+    private final TagRewriter<ClientboundPacket1_21> tagRewriter = new TagRewriter<>(this);
 
     public Protocol1_21To1_20_5() {
-        super(ClientboundPacket1_20_5.class, ClientboundPacket1_20_5.class, ServerboundPacket1_20_5.class, ServerboundPacket1_20_5.class);
+        super(ClientboundPacket1_21.class, ClientboundPacket1_20_5.class, ServerboundPacket1_20_5.class, ServerboundPacket1_20_5.class);
     }
 
     @Override
     protected void registerPackets() {
         super.registerPackets();
 
-        tagRewriter.registerGeneric(ClientboundPackets1_20_5.UPDATE_TAGS);
-        tagRewriter.registerGeneric(ClientboundConfigurationPackets1_20_5.UPDATE_TAGS);
+        tagRewriter.registerGeneric(ClientboundPackets1_21.UPDATE_TAGS);
+        tagRewriter.registerGeneric(ClientboundConfigurationPackets1_21.UPDATE_TAGS);
 
-        final SoundRewriter<ClientboundPacket1_20_5> soundRewriter = new SoundRewriter<>(this);
-        soundRewriter.registerSound1_19_3(ClientboundPackets1_20_5.SOUND);
-        soundRewriter.registerSound1_19_3(ClientboundPackets1_20_5.SOUND_ENTITY);
-        soundRewriter.registerStopSound(ClientboundPackets1_20_5.STOP_SOUND);
+        final SoundRewriter<ClientboundPacket1_21> soundRewriter = new SoundRewriter<>(this);
+        soundRewriter.registerSound1_19_3(ClientboundPackets1_21.SOUND);
+        soundRewriter.registerSound1_19_3(ClientboundPackets1_21.SOUND_ENTITY);
+        soundRewriter.registerStopSound(ClientboundPackets1_21.STOP_SOUND);
 
-        new StatisticsRewriter<>(this).register(ClientboundPackets1_20_5.AWARD_STATS);
-        new AttributeRewriter<>(this).register1_20_5(ClientboundPackets1_20_5.UPDATE_ATTRIBUTES);
+        new StatisticsRewriter<>(this).register(ClientboundPackets1_21.AWARD_STATS);
 
-        translatableRewriter.registerOpenScreen(ClientboundPackets1_20_5.OPEN_SCREEN);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.SET_ACTION_BAR_TEXT);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.SET_TITLE_TEXT);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.SET_SUBTITLE_TEXT);
-        translatableRewriter.registerBossEvent(ClientboundPackets1_20_5.BOSS_EVENT);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.DISCONNECT);
-        translatableRewriter.registerTabList(ClientboundPackets1_20_5.TAB_LIST);
-        translatableRewriter.registerPlayerCombatKill1_20(ClientboundPackets1_20_5.PLAYER_COMBAT_KILL);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.SYSTEM_CHAT);
-        translatableRewriter.registerComponentPacket(ClientboundPackets1_20_5.DISGUISED_CHAT);
+        translatableRewriter.registerOpenScreen(ClientboundPackets1_21.OPEN_SCREEN);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.SET_ACTION_BAR_TEXT);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.SET_TITLE_TEXT);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.SET_SUBTITLE_TEXT);
+        translatableRewriter.registerBossEvent(ClientboundPackets1_21.BOSS_EVENT);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.DISCONNECT);
+        translatableRewriter.registerTabList(ClientboundPackets1_21.TAB_LIST);
+        translatableRewriter.registerPlayerCombatKill1_20(ClientboundPackets1_21.PLAYER_COMBAT_KILL);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.SYSTEM_CHAT);
+        translatableRewriter.registerComponentPacket(ClientboundPackets1_21.DISGUISED_CHAT);
         translatableRewriter.registerPing();
 
         // Format change we can't properly map - all this really results in is a desync one version earlier
-        cancelClientbound(ClientboundPackets1_20_5.PROJECTILE_POWER);
+        cancelClientbound(ClientboundPackets1_21.PROJECTILE_POWER);
+
+        cancelClientbound(ClientboundPackets1_21.CUSTOM_REPORT_DETAILS);
+        cancelClientbound(ClientboundPackets1_21.SERVER_LINKS);
+        cancelClientbound(ClientboundConfigurationPackets1_21.CUSTOM_REPORT_DETAILS);
+        cancelClientbound(ClientboundConfigurationPackets1_21.SERVER_LINKS);
+
+        registerClientbound(ClientboundPackets1_21.UPDATE_ATTRIBUTES, wrapper -> {
+            wrapper.passthrough(Types.VAR_INT); // Entity ID
+
+            final int size = wrapper.passthrough(Types.VAR_INT);
+            int newSize = size;
+            for (int i = 0; i < size; i++) {
+                final int attributeId = wrapper.read(Types.VAR_INT);
+                final int mappedId = MAPPINGS.getNewAttributeId(attributeId);
+                if (mappedId == -1) {
+                    newSize--;
+
+                    wrapper.read(Types.DOUBLE); // Base
+                    final int modifierSize = wrapper.read(Types.VAR_INT);
+                    for (int j = 0; j < modifierSize; j++) {
+                        wrapper.read(Types.STRING); // ID
+                        wrapper.read(Types.DOUBLE); // Amount
+                        wrapper.read(Types.BYTE); // Operation
+                    }
+                    continue;
+                }
+
+                wrapper.write(Types.VAR_INT, mappedId);
+                wrapper.passthrough(Types.DOUBLE); // Base
+                final int modifierSize = wrapper.passthrough(Types.VAR_INT);
+                for (int j = 0; j < modifierSize; j++) {
+                    final String id = wrapper.read(Types.STRING);
+                    wrapper.write(Types.UUID, Protocol1_20_5To1_21.mapAttributeId(id));
+                    wrapper.passthrough(Types.DOUBLE); // Amount
+                    wrapper.passthrough(Types.BYTE); // Operation
+                }
+            }
+
+            if (size != newSize) {
+                wrapper.set(Types.VAR_INT, 1, newSize);
+            }
+        });
     }
 
     @Override
@@ -107,19 +152,19 @@ public final class Protocol1_21To1_20_5 extends BackwardsProtocol<ClientboundPac
     }
 
     @Override
-    public TranslatableRewriter<ClientboundPacket1_20_5> getTranslatableRewriter() {
+    public TranslatableRewriter<ClientboundPacket1_21> getTranslatableRewriter() {
         return translatableRewriter;
     }
 
     @Override
-    public TagRewriter<ClientboundPacket1_20_5> getTagRewriter() {
+    public TagRewriter<ClientboundPacket1_21> getTagRewriter() {
         return tagRewriter;
     }
 
     @Override
-    protected PacketTypesProvider<ClientboundPacket1_20_5, ClientboundPacket1_20_5, ServerboundPacket1_20_5, ServerboundPacket1_20_5> createPacketTypesProvider() {
+    protected PacketTypesProvider<ClientboundPacket1_21, ClientboundPacket1_20_5, ServerboundPacket1_20_5, ServerboundPacket1_20_5> createPacketTypesProvider() {
         return new SimplePacketTypesProvider<>(
-            packetTypeMap(unmappedClientboundPacketType, ClientboundPackets1_20_5.class, ClientboundConfigurationPackets1_20_5.class),
+            packetTypeMap(unmappedClientboundPacketType, ClientboundPackets1_21.class, ClientboundConfigurationPackets1_21.class),
             packetTypeMap(mappedClientboundPacketType, ClientboundPackets1_20_5.class, ClientboundConfigurationPackets1_20_5.class),
             packetTypeMap(mappedServerboundPacketType, ServerboundPackets1_20_5.class, ServerboundConfigurationPackets1_20_5.class),
             packetTypeMap(unmappedServerboundPacketType, ServerboundPackets1_20_5.class, ServerboundConfigurationPackets1_20_5.class)
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/BlockItemPacketRewriter1_21.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/BlockItemPacketRewriter1_21.java
index eec85715..d9235166 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/BlockItemPacketRewriter1_21.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/BlockItemPacketRewriter1_21.java
@@ -39,17 +39,20 @@ import com.viaversion.viaversion.api.type.types.version.Types1_21;
 import com.viaversion.viaversion.libs.fastutil.ints.Int2IntMap;
 import com.viaversion.viaversion.protocols.v1_20_2to1_20_3.rewriter.RecipeRewriter1_20_3;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.data.Enchantments1_20_5;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPacket1_20_5;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPackets1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundPacket1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ServerboundPackets1_20_5;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPacket1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPackets1_21;
 import com.viaversion.viaversion.rewriter.BlockRewriter;
 import com.viaversion.viaversion.rewriter.IdRewriteFunction;
 import java.util.ArrayList;
 import java.util.Arrays;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRewriter<ClientboundPacket1_20_5, ServerboundPacket1_20_5, Protocol1_21To1_20_5> {
+import static com.viaversion.viaversion.protocols.v1_20_5to1_21.rewriter.BlockItemPacketRewriter1_21.downgradeItemData;
+import static com.viaversion.viaversion.protocols.v1_20_5to1_21.rewriter.BlockItemPacketRewriter1_21.updateItemData;
+
+public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRewriter<ClientboundPacket1_21, ServerboundPacket1_20_5, Protocol1_21To1_20_5> {
 
     private final StructuredEnchantmentRewriter enchantmentRewriter = new StructuredEnchantmentRewriter(this);
 
@@ -59,25 +62,25 @@ public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRe
 
     @Override
     public void registerPackets() {
-        final BlockRewriter<ClientboundPacket1_20_5> blockRewriter = BlockRewriter.for1_20_2(protocol);
-        blockRewriter.registerBlockEvent(ClientboundPackets1_20_5.BLOCK_EVENT);
-        blockRewriter.registerBlockUpdate(ClientboundPackets1_20_5.BLOCK_UPDATE);
-        blockRewriter.registerSectionBlocksUpdate1_20(ClientboundPackets1_20_5.SECTION_BLOCKS_UPDATE);
-        blockRewriter.registerLevelEvent(ClientboundPackets1_20_5.LEVEL_EVENT, 1010, 2001);
-        blockRewriter.registerLevelChunk1_19(ClientboundPackets1_20_5.LEVEL_CHUNK_WITH_LIGHT, ChunkType1_20_2::new);
-        blockRewriter.registerBlockEntityData(ClientboundPackets1_20_5.BLOCK_ENTITY_DATA);
+        final BlockRewriter<ClientboundPacket1_21> blockRewriter = BlockRewriter.for1_20_2(protocol);
+        blockRewriter.registerBlockEvent(ClientboundPackets1_21.BLOCK_EVENT);
+        blockRewriter.registerBlockUpdate(ClientboundPackets1_21.BLOCK_UPDATE);
+        blockRewriter.registerSectionBlocksUpdate1_20(ClientboundPackets1_21.SECTION_BLOCKS_UPDATE);
+        blockRewriter.registerLevelEvent(ClientboundPackets1_21.LEVEL_EVENT, 1010, 2001);
+        blockRewriter.registerLevelChunk1_19(ClientboundPackets1_21.LEVEL_CHUNK_WITH_LIGHT, ChunkType1_20_2::new);
+        blockRewriter.registerBlockEntityData(ClientboundPackets1_21.BLOCK_ENTITY_DATA);
 
-        registerCooldown(ClientboundPackets1_20_5.COOLDOWN);
-        registerSetContent1_17_1(ClientboundPackets1_20_5.CONTAINER_SET_CONTENT);
-        registerSetSlot1_17_1(ClientboundPackets1_20_5.CONTAINER_SET_SLOT);
-        registerAdvancements1_20_3(ClientboundPackets1_20_5.UPDATE_ADVANCEMENTS);
-        registerSetEquipment(ClientboundPackets1_20_5.SET_EQUIPMENT);
+        registerCooldown(ClientboundPackets1_21.COOLDOWN);
+        registerSetContent1_17_1(ClientboundPackets1_21.CONTAINER_SET_CONTENT);
+        registerSetSlot1_17_1(ClientboundPackets1_21.CONTAINER_SET_SLOT);
+        registerAdvancements1_20_3(ClientboundPackets1_21.UPDATE_ADVANCEMENTS);
+        registerSetEquipment(ClientboundPackets1_21.SET_EQUIPMENT);
         registerContainerClick1_17_1(ServerboundPackets1_20_5.CONTAINER_CLICK);
-        registerMerchantOffers1_20_5(ClientboundPackets1_20_5.MERCHANT_OFFERS, Types1_21.ITEM_COST, Types1_20_5.ITEM_COST, Types1_21.OPTIONAL_ITEM_COST, Types1_20_5.OPTIONAL_ITEM_COST);
+        registerMerchantOffers1_20_5(ClientboundPackets1_21.MERCHANT_OFFERS, Types1_21.ITEM_COST, Types1_20_5.ITEM_COST, Types1_21.OPTIONAL_ITEM_COST, Types1_20_5.OPTIONAL_ITEM_COST);
         registerSetCreativeModeSlot(ServerboundPackets1_20_5.SET_CREATIVE_MODE_SLOT);
-        registerContainerSetData(ClientboundPackets1_20_5.CONTAINER_SET_DATA);
-        registerLevelParticles1_20_5(ClientboundPackets1_20_5.LEVEL_PARTICLES, Types1_21.PARTICLE, Types1_20_5.PARTICLE);
-        registerExplosion(ClientboundPackets1_20_5.EXPLODE, Types1_21.PARTICLE, Types1_20_5.PARTICLE);
+        registerContainerSetData(ClientboundPackets1_21.CONTAINER_SET_DATA);
+        registerLevelParticles1_20_5(ClientboundPackets1_21.LEVEL_PARTICLES, Types1_21.PARTICLE, Types1_20_5.PARTICLE);
+        registerExplosion(ClientboundPackets1_21.EXPLODE, Types1_21.PARTICLE, Types1_20_5.PARTICLE);
 
         protocol.registerServerbound(ServerboundPackets1_20_5.USE_ITEM, wrapper -> {
             wrapper.passthrough(Types.VAR_INT); // Hand
@@ -86,7 +89,7 @@ public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRe
             wrapper.write(Types.FLOAT, 0f); // X rotation
         });
 
-        new RecipeRewriter1_20_3<>(protocol).register1_20_5(ClientboundPackets1_20_5.UPDATE_RECIPES);
+        new RecipeRewriter1_20_3<>(protocol).register1_20_5(ClientboundPackets1_21.UPDATE_RECIPES);
     }
 
     @Override
@@ -117,6 +120,8 @@ public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRe
         enchantmentRewriter.rewriteEnchantmentsToClient(data, StructuredDataKey.ENCHANTMENTS, idRewriteFunction, descriptionSupplier, false);
         enchantmentRewriter.rewriteEnchantmentsToClient(data, StructuredDataKey.STORED_ENCHANTMENTS, idRewriteFunction, descriptionSupplier, true);
 
+        downgradeItemData(item);
+
         return super.handleItemToClient(connection, item);
     }
 
@@ -137,6 +142,8 @@ public final class BlockItemPacketRewriter1_21 extends BackwardsStructuredItemRe
         // Restore originals if present
         enchantmentRewriter.handleToServer(item);
 
+        updateItemData(item);
+
         return super.handleItemToServer(connection, item);
     }
 
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/EntityPacketRewriter1_21.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/EntityPacketRewriter1_21.java
index 32391da9..47203b29 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/EntityPacketRewriter1_21.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_21to1_20_5/rewriter/EntityPacketRewriter1_21.java
@@ -33,16 +33,16 @@ import com.viaversion.viaversion.api.protocol.remapper.PacketHandlers;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.version.Types1_20_5;
 import com.viaversion.viaversion.api.type.types.version.Types1_21;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundConfigurationPackets1_20_5;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPacket1_20_5;
-import com.viaversion.viaversion.protocols.v1_20_3to1_20_5.packet.ClientboundPackets1_20_5;
 import com.viaversion.viaversion.protocols.v1_20_5to1_21.data.Paintings1_20_5;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundConfigurationPackets1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPacket1_21;
+import com.viaversion.viaversion.protocols.v1_20_5to1_21.packet.ClientboundPackets1_21;
 import com.viaversion.viaversion.util.Key;
 import com.viaversion.viaversion.util.KeyMappings;
 import java.util.HashMap;
 import java.util.Map;
 
-public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPacket1_20_5, Protocol1_21To1_20_5> {
+public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPacket1_21, Protocol1_21To1_20_5> {
 
     private final Map<String, PaintingData> oldPaintings = new HashMap<>();
 
@@ -57,12 +57,17 @@ public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPa
 
     @Override
     public void registerPackets() {
-        registerTrackerWithData1_19(ClientboundPackets1_20_5.ADD_ENTITY, EntityTypes1_20_5.FALLING_BLOCK);
-        registerSetEntityData(ClientboundPackets1_20_5.SET_ENTITY_DATA, Types1_21.ENTITY_DATA_LIST, Types1_20_5.ENTITY_DATA_LIST);
-        registerRemoveEntities(ClientboundPackets1_20_5.REMOVE_ENTITIES);
+        registerTrackerWithData1_19(ClientboundPackets1_21.ADD_ENTITY, EntityTypes1_20_5.FALLING_BLOCK);
+        registerSetEntityData(ClientboundPackets1_21.SET_ENTITY_DATA, Types1_21.ENTITY_DATA_LIST, Types1_20_5.ENTITY_DATA_LIST);
+        registerRemoveEntities(ClientboundPackets1_21.REMOVE_ENTITIES);
 
-        protocol.registerClientbound(ClientboundConfigurationPackets1_20_5.REGISTRY_DATA, wrapper -> {
+        protocol.registerClientbound(ClientboundConfigurationPackets1_21.REGISTRY_DATA, wrapper -> {
             final String key = Key.stripMinecraftNamespace(wrapper.passthrough(Types.STRING));
+            if (key.equals("jukebox_song")) {
+                wrapper.cancel();
+                return;
+            }
+
             final RegistryEntry[] entries = wrapper.passthrough(Types.REGISTRY_ENTRY_ARRAY);
             final boolean paintingVariant = key.equals("painting_variant");
             if (paintingVariant || key.equals("enchantment")) {
@@ -92,7 +97,7 @@ public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPa
             }
         });
 
-        protocol.registerClientbound(ClientboundPackets1_20_5.LOGIN, new PacketHandlers() {
+        protocol.registerClientbound(ClientboundPackets1_21.LOGIN, new PacketHandlers() {
             @Override
             public void register() {
                 map(Types.INT); // Entity id
@@ -110,7 +115,7 @@ public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPa
             }
         });
 
-        protocol.registerClientbound(ClientboundPackets1_20_5.RESPAWN, wrapper -> {
+        protocol.registerClientbound(ClientboundPackets1_21.RESPAWN, wrapper -> {
             final int dimensionId = wrapper.passthrough(Types.VAR_INT);
             final String world = wrapper.passthrough(Types.STRING);
             trackWorldDataByKey1_20_5(wrapper.user(), dimensionId, world); // Tracks world height and name for chunk data and entity (un)tracking
@@ -151,7 +156,7 @@ public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPa
             if (type == Types1_21.ENTITY_DATA_TYPES.wolfVariantType) {
                 final Holder<WolfVariant> variant = data.value();
                 if (variant.hasId()) {
-                    data.setTypeAndValue(Types1_20_5.ENTITY_DATA_TYPES.wolfVariantType, variant);
+                    data.setTypeAndValue(Types1_20_5.ENTITY_DATA_TYPES.wolfVariantType, variant.id());
                 } else {
                     event.cancel();
                 }
@@ -168,7 +173,6 @@ public final class EntityPacketRewriter1_21 extends EntityRewriter<ClientboundPa
                 data.setDataType(Types1_20_5.ENTITY_DATA_TYPES.byId(type.typeId()));
             }
         });
-        filter().mapDataType(Types1_20_5.ENTITY_DATA_TYPES::byId);
 
         registerMetaTypeHandler1_20_3(
             Types1_20_5.ENTITY_DATA_TYPES.itemType,
diff --git a/common/src/main/resources/assets/viabackwards/data/mappings-1.21to1.20.5.nbt b/common/src/main/resources/assets/viabackwards/data/mappings-1.21to1.20.5.nbt
index 16580da3..7d4fcecd 100644
Binary files a/common/src/main/resources/assets/viabackwards/data/mappings-1.21to1.20.5.nbt and b/common/src/main/resources/assets/viabackwards/data/mappings-1.21to1.20.5.nbt differ
diff --git a/common/src/main/resources/assets/viabackwards/data/translation-mappings.json b/common/src/main/resources/assets/viabackwards/data/translation-mappings.json
index 137bb38b..898fe93e 100644
--- a/common/src/main/resources/assets/viabackwards/data/translation-mappings.json
+++ b/common/src/main/resources/assets/viabackwards/data/translation-mappings.json
@@ -1,4 +1,106 @@
 {
+  "1.21": {
+    "argument.entity.selector.nearestEntity": "Nearest entity",
+    "attribute.name.generic.burning_time": "Burning Time",
+    "attribute.name.generic.explosion_knockback_resistance": "Explosion Knockback Resistance",
+    "attribute.name.generic.movement_efficiency": "Movement Efficiency",
+    "attribute.name.generic.oxygen_bonus": "Oxygen Bonus",
+    "attribute.name.generic.water_movement_efficiency": "Water Movement Efficiency",
+    "attribute.name.player.mining_efficiency": "Mining Efficiency",
+    "attribute.name.player.sneaking_speed": "Sneaking Speed",
+    "attribute.name.player.submerged_mining_speed": "Submerged Mining Speed",
+    "attribute.name.player.sweeping_damage_ratio": "Sweeping Damage Ratio",
+    "gamerule.entitiesWithPassengersCanUsePortals": "Entities with passengers can use portals",
+    "gamerule.entitiesWithPassengersCanUsePortals.description": "Allow entities with passengers to teleport through nether portals, end portals and end gateways.",
+    "gui.fileDropFailure.detail": "Rejected %d files",
+    "gui.fileDropFailure.title": "Failed to add files",
+    "gui.open_report_dir": "Open Report Directory",
+    "gui.report_to_server": "Report To Server",
+    "item.minecraft.music_disc_creator": "Music Disc",
+    "item.minecraft.music_disc_creator_music_box": "Music Disc",
+    "item.minecraft.music_disc_creator_music_box.desc": "Lena Raine - Creator (Music Box)",
+    "item.minecraft.music_disc_creator.desc": "Lena Raine - Creator",
+    "item.minecraft.music_disc_precipice": "Music Disc",
+    "item.minecraft.music_disc_precipice.desc": "Aaron Cherof - Precipice",
+    "item.modifiers.any": "When equipped:",
+    "item.modifiers.armor": "When worn:",
+    "item.modifiers.hand": "When held:",
+    "jukebox_song.minecraft.5": "Samuel �berg - 5",
+    "jukebox_song.minecraft.11": "C418 - 11",
+    "jukebox_song.minecraft.13": "C418 - 13",
+    "jukebox_song.minecraft.blocks": "C418 - blocks",
+    "jukebox_song.minecraft.cat": "C418 - cat",
+    "jukebox_song.minecraft.chirp": "C418 - chirp",
+    "jukebox_song.minecraft.creator": "Lena Raine - Creator",
+    "jukebox_song.minecraft.creator_music_box": "Lena Raine - Creator (Music Box)",
+    "jukebox_song.minecraft.far": "C418 - far",
+    "jukebox_song.minecraft.mall": "C418 - mall",
+    "jukebox_song.minecraft.mellohi": "C418 - mellohi",
+    "jukebox_song.minecraft.otherside": "Lena Raine - otherside",
+    "jukebox_song.minecraft.pigstep": "Lena Raine - Pigstep",
+    "jukebox_song.minecraft.precipice": "Aaron Cherof - Precipice",
+    "jukebox_song.minecraft.relic": "Aaron Cherof - Relic",
+    "jukebox_song.minecraft.stal": "C418 - stal",
+    "jukebox_song.minecraft.strad": "C418 - strad",
+    "jukebox_song.minecraft.wait": "C418 - wait",
+    "jukebox_song.minecraft.ward": "C418 - ward",
+    "known_server_link.report_bug": "Report Server Bug",
+    "mco.compatibility.incompatible.popup.title": "Incompatible version",
+    "mco.compatibility.incompatible.releaseType.popup.message": "The world you are trying to join is incompatible with the version you are on.",
+    "mco.compatibility.incompatible.series.popup.message": "This world was last played in version %s; you are on version %s.\n\nThese series are not compatible with each other. A new world is needed to play on this version.",
+    "mco.compatibility.upgrade.friend.description": "This world was last played in version %s; you are on version %s.\n\nA backup of the world will be saved under \"World Backups\".\n\nThe owner of the Realm can restore the world if needed.",
+    "mco.configure.world.resourcepack.question": "You need a custom resource pack to play on this realm\n\nDo you want to download it and play?",
+    "mco.download.confirmation.oversized": "The world you are going to download is larger than %s\n\nYou won't be able to upload this world to your realm again",
+    "mco.onlinePlayers": "Online Players",
+    "menu.feedback": "Feedback...",
+    "menu.feedback.title": "Feedback",
+    "menu.server_links": "Server Links...",
+    "menu.server_links.title": "Server Links",
+    "options.realmsNotifications.tooltip": "Fetches Realms news and invites in the title screen and displays their respective icon on the Realms button.",
+    "painting.minecraft.backyard.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.backyard.title": "Backyard",
+    "painting.minecraft.baroque.author": "Sarah Boeving",
+    "painting.minecraft.baroque.title": "Baroque",
+    "painting.minecraft.bouquet.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.bouquet.title": "Bouquet",
+    "painting.minecraft.cavebird.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.cavebird.title": "Cavebird",
+    "painting.minecraft.changing.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.changing.title": "Changing",
+    "painting.minecraft.cotan.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.cotan.title": "Cot�n",
+    "painting.minecraft.endboss.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.endboss.title": "Endboss",
+    "painting.minecraft.fern.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.fern.title": "Fern",
+    "painting.minecraft.finding.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.finding.title": "Finding",
+    "painting.minecraft.humble.author": "Sarah Boeving",
+    "painting.minecraft.humble.title": "Humble",
+    "painting.minecraft.lowmist.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.lowmist.title": "Lowmist",
+    "painting.minecraft.meditative.author": "Sarah Boeving",
+    "painting.minecraft.meditative.title": "Meditative",
+    "painting.minecraft.orb.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.orb.title": "Orb",
+    "painting.minecraft.owlemons.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.owlemons.title": "Owlemons",
+    "painting.minecraft.passage.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.passage.title": "Passage",
+    "painting.minecraft.pond.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.pond.title": "Pond",
+    "painting.minecraft.prairie_ride.author": "Sarah Boeving",
+    "painting.minecraft.prairie_ride.title": "Prairie Ride",
+    "painting.minecraft.sunflowers.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.sunflowers.title": "Sunflowers",
+    "painting.minecraft.tides.author": "Kristoffer Zetterstrand",
+    "painting.minecraft.tides.title": "Tides",
+    "painting.minecraft.unpacked.author": "Sarah Boeving",
+    "painting.minecraft.unpacked.title": "Unpacked",
+    "subtitles.block.trial_spawner.ambient_ominous": "Ominous crackling",
+    "subtitles.block.trial_spawner.ominous_activate": "Omen engulfs Trial Spawner",
+    "subtitles.block.vault.reject_rewarded_player": "Vault rejects already rewarded player"
+  },
   "1.20.5": {
     "advancements.adventure.blowback.description": "Kill a Breeze with a deflected Breeze-shot Wind Charge",
     "advancements.adventure.blowback.title": "Blowback",
diff --git a/gradle.properties b/gradle.properties
index b7780858..0e6bc16e 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,4 +1,4 @@
-projectVersion=5.0.0-24w20a-SNAPSHOT
+projectVersion=5.0.0-24w21b-SNAPSHOT
 
 # Smile emoji
 mcVersions=1.20.6,1.20.5,1.20.4, 1.20.3, 1.20.2, 1.20.1, 1.20, 1.19.4, 1.19.3, 1.19.2, 1.19.1, 1.19, 1.18.2, 1.18.1, 1.18, 1.17.1, 1.17, 1.16.5, 1.16.4, 1.16.3, 1.16.2, 1.16.1, 1.16, 1.15.2, 1.15.1, 1.15, 1.14.4, 1.14.3, 1.14.2, 1.14.1, 1.14, 1.13.2, 1.13.1, 1.13, 1.12.2, 1.12.1, 1.12, 1.11.2, 1.11.1, 1.11, 1.10.2, 1.10.1, 1.10
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 50b5dd13..85907022 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -3,7 +3,7 @@ metadata.format.version = "1.1"
 [versions]
 
 # ViaVersion
-viaver = "5.0.0-24w20a-SNAPSHOT"
+viaver = "5.0.0-24w21a-SNAPSHOT"
 
 # Common provided
 netty = "4.0.20.Final"
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 440aa545..b1053759 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -4,6 +4,7 @@ rootProject.name = "viabackwards-parent"
 
 dependencyResolutionManagement {
     repositories {
+        mavenLocal()
         maven("https://repo.viaversion.com")
         maven("https://repo.papermc.io/repository/maven-public/")
         mavenCentral()
diff --git a/template/src/main/java/com/viaversion/viabackwards/template/protocol/Protocol1_98To1_99.java b/template/src/main/java/com/viaversion/viabackwards/template/protocol/Protocol1_98To1_99.java
index e040897a..36888203 100644
--- a/template/src/main/java/com/viaversion/viabackwards/template/protocol/Protocol1_98To1_99.java
+++ b/template/src/main/java/com/viaversion/viabackwards/template/protocol/Protocol1_98To1_99.java
@@ -76,7 +76,7 @@ public final class Protocol1_98To1_99 extends BackwardsProtocol<ClientboundPacke
         soundRewriter.registerStopSound(ClientboundPackets1_20_5.STOP_SOUND);
 
         new StatisticsRewriter<>(this).register(ClientboundPackets1_20_5.AWARD_STATS);
-        //new AttributeRewriter<>(this).register1_20_5(ClientboundPackets1_20_5.ENTITY_PROPERTIES);
+        //new AttributeRewriter<>(this).register1_21(ClientboundPackets1_20_5.ENTITY_PROPERTIES);
 
         // Registers translatable mappings (missing a whole bunch still)
         //translatableRewriter.registerOpenWindow(ClientboundPackets1_20_5.OPEN_WINDOW); // Handled by registerOpenWindow in item rewriters