diff --git a/index.d.ts b/index.d.ts
index 8127770492b..b155be8391d 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -212,10 +212,7 @@ declare namespace WAWebJS {
         ): Promise<Message>;
 
         /** Send a reaction to a specific messageId */
-        sendReaction(
-            messageId: string,
-            reaction: string,
-        ): Promise<void>;
+        sendReaction(messageId: string, reaction: string): Promise<void>;
 
         /** Sends a channel admin invitation to a user, allowing them to become an admin of the channel */
         sendChannelAdminInvite(
diff --git a/src/Client.js b/src/Client.js
index a122a8f336b..62de5395407 100644
--- a/src/Client.js
+++ b/src/Client.js
@@ -1234,7 +1234,8 @@ class Client extends EventEmitter {
                             const parentMsgKey = reaction.reactionParentKey;
                             const timestamp = reaction.reactionTimestamp / 1000;
                             const sender = reaction.author ?? reaction.from;
-                            const senderUserJid = sender._serialized;
+                            const senderUserJid =
+                                sender._serialized || sender.$1;
 
                             return {
                                 ...reaction,
@@ -1262,14 +1263,15 @@ class Client extends EventEmitter {
                             const parentMsgKey = vote.pollUpdateParentKey;
                             const timestamp = vote.t / 1000;
                             const sender = vote.author ?? vote.from;
-                            const senderUserJid = sender._serialized;
+                            const senderUserJid =
+                                sender._serialized || sender.$1;
 
                             let parentMessage = Msg.get(
-                                parentMsgKey._serialized,
+                                parentMsgKey._serialized || parentMsgKey.$1,
                             );
                             if (!parentMessage) {
                                 const fetched = await Msg.getMessagesById([
-                                    parentMsgKey._serialized,
+                                    parentMsgKey._serialized || parentMsgKey.$1,
                                 ]);
                                 parentMessage = fetched?.messages?.[0] || null;
                             }
@@ -1898,7 +1900,7 @@ class Client extends EventEmitter {
                 .joinGroupViaInvite(inviteCode);
         }, inviteCode);
 
-        return res.gid._serialized;
+        return res.gid._serialized || res.gid.$1;
     }
 
     /**
@@ -2442,7 +2444,8 @@ class Client extends EventEmitter {
                         (participant.wid = window
                             .require('WAWebApiContact')
                             .getPhoneNumber(participant.wid));
-                    const participantId = participant.wid._serialized;
+                    const participantId =
+                        participant.wid._serialized || participant.wid.$1;
                     const statusCode = participant.error || 200;
 
                     if (autoSendInviteV4 && statusCode === 403) {
@@ -2458,7 +2461,8 @@ class Client extends EventEmitter {
                                     (await window
                                         .require('WAWebCollections')
                                         .Chat.find(participant.wid)),
-                                createGroupResult.wid._serialized,
+                                createGroupResult.wid._serialized ||
+                                    createGroupResult.wid.$1,
                                 createGroupResult.subject,
                                 participant.invite_code,
                                 participant.invite_code_exp,
@@ -2932,7 +2936,7 @@ class Client extends EventEmitter {
             let chatIds = window
                 .require('WAWebCollections')
                 .Blocklist.getModelsArray()
-                .map((a) => a.id._serialized);
+                .map((a) => a.id._serialized || a.id.$1);
             return Promise.all(
                 chatIds.map((id) => window.WWebJS.getContact(id)),
             );
@@ -2993,7 +2997,9 @@ class Client extends EventEmitter {
                 );
                 const chats = window
                     .require('WAWebCollections')
-                    .Chat.filter((e) => chatIds.includes(e.id._serialized));
+                    .Chat.filter((e) =>
+                        chatIds.includes(e.id._serialized || e.id.$1),
+                    );
 
                 let actions = labels.map((label) => ({
                     id: label.id,
@@ -3374,8 +3380,8 @@ class Client extends EventEmitter {
                         await window.WWebJS.enforceLidAndPnRetrieval(userId);
 
                     return {
-                        lid: lid?._serialized,
-                        pn: phone?._serialized,
+                        lid: lid?._serialized || lid?.$1,
+                        pn: phone?._serialized || phone?.$1,
                     };
                 }),
             );
@@ -3446,9 +3452,12 @@ class Client extends EventEmitter {
 
             if (!serialized) return null;
 
-            serialized.chatId = window
-                .require('WAWebJidToWid')
-                .userJidToUserWid(serialized.chatJid)._serialized;
+            serialized.chatId = (() => {
+                const _w = window
+                    .require('WAWebJidToWid')
+                    .userJidToUserWid(serialized.chatJid);
+                return _w._serialized || _w.$1;
+            })();
             delete serialized.chatJid;
 
             return serialized;
diff --git a/src/structures/Base.js b/src/structures/Base.js
index ed1d83c09e6..a22afdf817a 100644
--- a/src/structures/Base.js
+++ b/src/structures/Base.js
@@ -19,6 +19,20 @@ class Base {
     _patch(data) {
         return data;
     }
+
+    /**
+     * Normalizes a WhatsApp ID object so that `_serialized` is always defined.
+     * WhatsApp Web changed `_serialized` to `$1` in July 2026. This ensures
+     * backward compatibility so all downstream code can continue using `_serialized`.
+     * @param {object} id
+     * @returns {object}
+     */
+    static _normalizeId(id) {
+        if (id && id._serialized == null && id.$1 != null) {
+            return Object.assign({}, id, { _serialized: id.$1 });
+        }
+        return id;
+    }
 }
 
 module.exports = Base;
diff --git a/src/structures/Broadcast.js b/src/structures/Broadcast.js
index ce03dfaf5fc..f0bbb8ed330 100644
--- a/src/structures/Broadcast.js
+++ b/src/structures/Broadcast.js
@@ -19,7 +19,7 @@ class Broadcast extends Base {
          * ID that represents the chat
          * @type {object}
          */
-        this.id = data.id;
+        this.id = Base._normalizeId(data.id);
 
         /**
          * Unix timestamp of last status
diff --git a/src/structures/Channel.js b/src/structures/Channel.js
index cd3e08786fe..25181de6b86 100644
--- a/src/structures/Channel.js
+++ b/src/structures/Channel.js
@@ -29,7 +29,7 @@ class Channel extends Base {
          * ID that represents the channel
          * @type {ChannelId}
          */
-        this.id = data.id;
+        this.id = Base._normalizeId(data.id);
 
         /**
          * Title of the channel
diff --git a/src/structures/Chat.js b/src/structures/Chat.js
index 40211bf04d4..79624e34430 100644
--- a/src/structures/Chat.js
+++ b/src/structures/Chat.js
@@ -19,7 +19,7 @@ class Chat extends Base {
          * ID that represents the chat
          * @type {object}
          */
-        this.id = data.id;
+        this.id = Base._normalizeId(data.id);
 
         /**
          * Title of the chat
diff --git a/src/structures/ClientInfo.js b/src/structures/ClientInfo.js
index 8e273c16a8d..de3dece19d9 100644
--- a/src/structures/ClientInfo.js
+++ b/src/structures/ClientInfo.js
@@ -24,7 +24,7 @@ class ClientInfo extends Base {
          * Current user ID
          * @type {object}
          */
-        this.wid = data.wid;
+        this.wid = Base._normalizeId(data.wid);
 
         /**
          * @type {object}
diff --git a/src/structures/Contact.js b/src/structures/Contact.js
index 339fa5c9e51..b56c967aa94 100644
--- a/src/structures/Contact.js
+++ b/src/structures/Contact.js
@@ -26,7 +26,7 @@ class Contact extends Base {
          * ID that represents the contact
          * @type {ContactId}
          */
-        this.id = data.id;
+        this.id = Base._normalizeId(data.id);
 
         /**
          * Contact's phone number
@@ -196,7 +196,7 @@ class Contact extends Base {
 
                 contact = await window
                     .require('WAWebCollections')
-                    .Contact.find(lid._serialized);
+                    .Contact.find(lid._serialized || lid.$1);
             }
             await window
                 .require('WAWebBlockContactAction')
diff --git a/src/structures/GroupChat.js b/src/structures/GroupChat.js
index 3cecc82845b..b9049d472cc 100644
--- a/src/structures/GroupChat.js
+++ b/src/structures/GroupChat.js
@@ -156,7 +156,7 @@ class GroupChat extends Chat {
                 };
 
                 for (let pWid of participantWids) {
-                    const pId = pWid._serialized;
+                    const pId = pWid._serialized || pWid.$1;
                     pWid =
                         pWid.server === 'lid'
                             ? window
@@ -170,7 +170,11 @@ class GroupChat extends Chat {
                         isInviteV4Sent: false,
                     };
 
-                    if (groupParticipants.some((p) => p._serialized === pId)) {
+                    if (
+                        groupParticipants.some(
+                            (p) => (p._serialized || p.$1) === pId,
+                        )
+                    ) {
                         participantData[pId].code = 409;
                         participantData[pId].message = errorCodes[409];
                         continue;
@@ -223,7 +227,7 @@ class GroupChat extends Chat {
                                 .require('WAWebChatSendMessages')
                                 .sendGroupInviteMessage(
                                     userChat,
-                                    group.id._serialized,
+                                    group.id._serialized || group.id.$1,
                                     groupName,
                                     rpcResult.inviteV4Code,
                                     rpcResult.inviteV4CodeExp,
@@ -274,10 +278,10 @@ class GroupChat extends Chat {
 
                             return (
                                 chat.groupMetadata.participants.get(
-                                    lid?._serialized,
+                                    lid?._serialized || lid?.$1,
                                 ) ||
                                 chat.groupMetadata.participants.get(
-                                    phone?._serialized,
+                                    phone?._serialized || phone?.$1,
                                 )
                             );
                         }),
@@ -312,10 +316,10 @@ class GroupChat extends Chat {
 
                             return (
                                 chat.groupMetadata.participants.get(
-                                    lid?._serialized,
+                                    lid?._serialized || lid?.$1,
                                 ) ||
                                 chat.groupMetadata.participants.get(
-                                    phone?._serialized,
+                                    phone?._serialized || phone?.$1,
                                 )
                             );
                         }),
@@ -350,10 +354,10 @@ class GroupChat extends Chat {
 
                             return (
                                 chat.groupMetadata.participants.get(
-                                    lid?._serialized,
+                                    lid?._serialized || lid?.$1,
                                 ) ||
                                 chat.groupMetadata.participants.get(
-                                    phone?._serialized,
+                                    phone?._serialized || phone?.$1,
                                 )
                             );
                         }),
diff --git a/src/structures/GroupNotification.js b/src/structures/GroupNotification.js
index a723639f4ef..61d597851aa 100644
--- a/src/structures/GroupNotification.js
+++ b/src/structures/GroupNotification.js
@@ -18,7 +18,7 @@ class GroupNotification extends Base {
          * ID that represents the groupNotification
          * @type {object}
          */
-        this.id = data.id;
+        this.id = Base._normalizeId(data.id);
 
         /**
          * Extra content
@@ -45,7 +45,7 @@ class GroupNotification extends Base {
          */
         this.chatId =
             typeof data.id.remote === 'object'
-                ? data.id.remote._serialized
+                ? data.id.remote._serialized || data.id.remote.$1
                 : data.id.remote;
 
         /**
@@ -54,7 +54,7 @@ class GroupNotification extends Base {
          */
         this.author =
             typeof data.author === 'object'
-                ? data.author._serialized
+                ? data.author._serialized || data.author.$1
                 : data.author;
 
         /**
diff --git a/src/structures/Message.js b/src/structures/Message.js
index 51e9062dbc0..ed7991352d7 100644
--- a/src/structures/Message.js
+++ b/src/structures/Message.js
@@ -35,7 +35,9 @@ class Message extends Base {
          * ID that represents the message
          * @type {object}
          */
-        this.id = data.id;
+        // Normalize id: WhatsApp Web changed _serialized to $1 in 2026-07 update.
+        // Keep _serialized always populated for backward compatibility.
+        this.id = Base._normalizeId(data.id);
 
         /**
          * ACK status for the message
@@ -75,7 +77,7 @@ class Message extends Base {
          */
         this.from =
             typeof data.from === 'object' && data.from !== null
-                ? data.from._serialized
+                ? data.from._serialized || data.from.$1
                 : data.from;
 
         /**
@@ -87,7 +89,7 @@ class Message extends Base {
          */
         this.to =
             typeof data.to === 'object' && data.to !== null
-                ? data.to._serialized
+                ? data.to._serialized || data.to.$1
                 : data.to;
 
         /**
@@ -96,7 +98,7 @@ class Message extends Base {
          */
         this.author =
             typeof data.author === 'object' && data.author !== null
-                ? data.author._serialized
+                ? data.author._serialized || data.author.$1
                 : data.author;
 
         /**
@@ -211,13 +213,13 @@ class Message extends Base {
                       groupName: data.inviteGrpName,
                       fromId:
                           typeof data.from === 'object' &&
-                          '_serialized' in data.from
-                              ? data.from._serialized
+                          (data.from._serialized || data.from.$1)
+                              ? data.from._serialized || data.from.$1
                               : data.from,
                       toId:
                           typeof data.to === 'object' &&
-                          '_serialized' in data.to
-                              ? data.to._serialized
+                          (data.to._serialized || data.to.$1)
+                              ? data.to._serialized || data.to.$1
                               : data.to,
                   }
                 : undefined;
diff --git a/src/util/Injected/Utils.js b/src/util/Injected/Utils.js
index dfa30a579de..b7e23bc7fe7 100644
--- a/src/util/Injected/Utils.js
+++ b/src/util/Injected/Utils.js
@@ -582,7 +582,7 @@ exports.LoadUtils = () => {
 
         return window
             .require('WAWebCollections')
-            .Msg.get(newMsgKey._serialized);
+            .Msg.get(newMsgKey._serialized || newMsgKey.$1);
     };
 
     window.WWebJS.editMessage = async (msg, content, options = {}) => {
@@ -625,7 +625,9 @@ exports.LoadUtils = () => {
         await window
             .require('WAWebSendMessageEditAction')
             .sendMessageEdit(msg, content, internalOptions);
-        return window.require('WAWebCollections').Msg.get(msg.id._serialized);
+        return window
+            .require('WAWebCollections')
+            .Msg.get(msg.id._serialized || msg.id.$1);
     };
 
     window.WWebJS.toStickerData = async (mediaInfo) => {
@@ -830,10 +832,16 @@ exports.LoadUtils = () => {
 
         if (typeof msg.id.remote === 'object') {
             msg.id = Object.assign({}, msg.id, {
-                remote: msg.id.remote._serialized,
+                remote: msg.id.remote._serialized || msg.id.remote.$1,
             });
         }
 
+        // WhatsApp Web changed _serialized to $1 in message IDs (2026-07 update).
+        // Normalize here so all downstream Node.js code can keep using _serialized.
+        if (msg.id && msg.id._serialized == null && msg.id.$1 != null) {
+            msg.id = Object.assign({}, msg.id, { _serialized: msg.id.$1 });
+        }
+
         delete msg.pendingAckUpdate;
 
         return msg;
@@ -953,7 +961,7 @@ exports.LoadUtils = () => {
             model.isGroup = true;
             const chatWid = window
                 .require('WAWebWidFactory')
-                .createWid(chat.id._serialized);
+                .createWid(chat.id._serialized || chat.id.$1);
             const groupMetadata =
                 window.require('WAWebCollections').GroupMetadata ||
                 window.require('WAWebCollections').WAWebGroupMetadataCollection;
@@ -981,16 +989,17 @@ exports.LoadUtils = () => {
 
         model.lastMessage = null;
         if (model.msgs && model.msgs.length) {
-            const lastMessage = chat.lastReceivedKey
+            const _lastReceivedKeyId = chat.lastReceivedKey
+                ? chat.lastReceivedKey._serialized || chat.lastReceivedKey.$1
+                : null;
+            const lastMessage = _lastReceivedKeyId
                 ? window
                       .require('WAWebCollections')
-                      .Msg.get(chat.lastReceivedKey._serialized) ||
+                      .Msg.get(_lastReceivedKeyId) ||
                   (
                       await window
                           .require('WAWebCollections')
-                          .Msg.getMessagesById([
-                              chat.lastReceivedKey._serialized,
-                          ])
+                          .Msg.getMessagesById([_lastReceivedKeyId])
                   )?.messages?.[0]
                 : null;
             lastMessage &&
@@ -1320,9 +1329,10 @@ exports.LoadUtils = () => {
     };
 
     window.WWebJS.rejectCall = async (peerJid, id) => {
-        let userId = window
+        const _meUser = window
             .require('WAWebUserPrefsMeUser')
-            .getMaybeMePnUser()._serialized;
+            .getMaybeMePnUser();
+        let userId = _meUser._serialized || _meUser.$1;
 
         const stanza = window.require('WAWap').wap(
             'call',
@@ -1632,9 +1642,12 @@ exports.LoadUtils = () => {
                                       .membershipRequestsActionRejectParticipantMixins
                                       ?.value.error;
                             return {
-                                requesterId: window
-                                    .require('WAWebWidFactory')
-                                    .createWid(p.jid)._serialized,
+                                requesterId: (() => {
+                                    const _w = window
+                                        .require('WAWebWidFactory')
+                                        .createWid(p.jid);
+                                    return _w._serialized || _w.$1;
+                                })(),
                                 ...(error
                                     ? {
                                           error: +error,
@@ -1651,11 +1664,15 @@ exports.LoadUtils = () => {
                     }
                 } else {
                     result.push({
-                        requesterId: window
-                            .require('WAWebJidToWid')
-                            .userJidToUserWid(
-                                participant.participantArgs[0].participantJid,
-                            )._serialized,
+                        requesterId: (() => {
+                            const _w = window
+                                .require('WAWebJidToWid')
+                                .userJidToUserWid(
+                                    participant.participantArgs[0]
+                                        .participantJid,
+                                );
+                            return _w._serialized || _w.$1;
+                        })(),
                         message: 'ServerStatusCodeError',
                     });
                 }