diff --git a/backend/open_webui/socket/main.py b/backend/open_webui/socket/main.py
index 00af651d6a..c3678f592d 100644
--- a/backend/open_webui/socket/main.py
+++ b/backend/open_webui/socket/main.py
@@ -5,6 +5,7 @@ import logging
 import random
 import sys
 import time
+from typing import Any
 
 import pycrdt as Y
 import socketio
@@ -47,6 +48,7 @@ from open_webui.utils.redis import (
     get_redis_connection,
     get_sentinels_from_env,
 )
+from socketio.packet import Packet
 
 logging.basicConfig(stream=sys.stdout, level=GLOBAL_LOG_LEVEL)
 log = logging.getLogger(__name__)
@@ -65,6 +67,17 @@ def get_room_sid_map(manager, namespace: str, room: str):
     return manager.rooms.get(namespace, {}).get(room)
 
 
+class JSONOnlyPacket(Packet):
+    """Packet class for JSON-serializable payloads only, skipping python-socketio's per-emit binary scan."""
+
+    uses_binary_events = False
+
+    @classmethod
+    def reconstruct_binary(cls, data: Any, attachments: list[bytes]):
+        """Normalize client attachments to int lists, the form the Yjs handlers store and apply."""
+        return super().reconstruct_binary(data, [list(attachment) for attachment in attachments])
+
+
 if WEBSOCKET_MANAGER == 'redis':
     sentinel_hosts = WEBSOCKET_SENTINEL_HOSTS or ''
     ws_redis_url = (
@@ -77,6 +90,7 @@ if WEBSOCKET_MANAGER == 'redis':
         cors_allowed_origins=SOCKETIO_CORS_ORIGINS,
         async_mode='asgi',
         json=SOCKETIO_JSON,
+        serializer=JSONOnlyPacket,
         transports=(['websocket'] if ENABLE_WEBSOCKET_SUPPORT else ['polling']),
         allow_upgrades=ENABLE_WEBSOCKET_SUPPORT,
         always_connect=True,
@@ -91,6 +105,7 @@ else:
         cors_allowed_origins=SOCKETIO_CORS_ORIGINS,
         async_mode='asgi',
         json=SOCKETIO_JSON,
+        serializer=JSONOnlyPacket,
         transports=(['websocket'] if ENABLE_WEBSOCKET_SUPPORT else ['polling']),
         allow_upgrades=ENABLE_WEBSOCKET_SUPPORT,
         always_connect=True,
diff --git a/src/lib/components/common/RichTextInput/Collaboration.ts b/src/lib/components/common/RichTextInput/Collaboration.ts
index 539da07a1e..1ef1c063ae 100644
--- a/src/lib/components/common/RichTextInput/Collaboration.ts
+++ b/src/lib/components/common/RichTextInput/Collaboration.ts
@@ -163,7 +163,7 @@ export class SocketIOCollaborationProvider {
 										document_id: this.documentId,
 										user_id: this.user?.id,
 										socket_id: this.socket.id,
-										update: Y.encodeStateAsUpdate(this.doc)
+										update: Array.from(Y.encodeStateAsUpdate(this.doc))
 									});
 								} else {
 									console.warn('Yjs document is empty, not sending state.');