diff --git a/src/memos/api/handlers/component_init.py b/src/memos/api/handlers/component_init.py
index 76af6decf..bfbd6271d 100644
--- a/src/memos/api/handlers/component_init.py
+++ b/src/memos/api/handlers/component_init.py
@@ -133,19 +133,22 @@ def init_server() -> dict[str, Any]:
     logger.info("Initializing MemOS server components...")
 
     # Initialize Redis client first as it is a core dependency for features like scheduler status tracking
-    try:
-        from memos.mem_scheduler.orm_modules.api_redis_model import APIRedisDBManager
-
-        redis_client = APIRedisDBManager.load_redis_engine_from_env()
-        if redis_client:
-            logger.info("Redis client initialized successfully.")
-        else:
-            logger.error(
-                "Failed to initialize Redis client. Check REDIS_HOST etc. in environment variables."
-            )
-    except Exception as e:
-        logger.error(f"Failed to initialize Redis client: {e}", exc_info=True)
-        redis_client = None  # Ensure redis_client exists even on failure
+    if os.getenv("MEMSCHEDULER_USE_REDIS_QUEUE", "False").lower() == "true":
+        try:
+            from memos.mem_scheduler.orm_modules.api_redis_model import APIRedisDBManager
+
+            redis_client = APIRedisDBManager.load_redis_engine_from_env()
+            if redis_client:
+                logger.info("Redis client initialized successfully.")
+            else:
+                logger.error(
+                    "Failed to initialize Redis client. Check REDIS_HOST etc. in environment variables."
+                )
+        except Exception as e:
+            logger.error(f"Failed to initialize Redis client: {e}", exc_info=True)
+            redis_client = None  # Ensure redis_client exists even on failure
+    else:
+        redis_client = None
 
     # Get default cube configuration
     default_cube_config = APIConfig.get_default_cube_config()
diff --git a/src/memos/api/handlers/formatters_handler.py b/src/memos/api/handlers/formatters_handler.py
index 29e376d33..6e1d9d1b6 100644
--- a/src/memos/api/handlers/formatters_handler.py
+++ b/src/memos/api/handlers/formatters_handler.py
@@ -144,7 +144,7 @@ def separate_knowledge_and_conversation_mem(memories: list[dict[str, Any]]):
     knowledge_mem = []
     conversation_mem = []
     for item in memories:
-        sources = item["metadata"]["sources"]
+        sources = item.get("metadata", {}).get("sources", [])
         if (
             len(sources) > 0
             and "type" in sources[0]
@@ -199,7 +199,7 @@ def rerank_knowledge_mem(
         item["metadata"]["sources"] = []
 
     for item in conversation_mem:
-        item["metadata"]["sources"] = []
+        item.setdefault("metadata", {})["sources"] = []
 
     # deduplicate: remove items with duplicate memory content
     original_count = len(reranked_knowledge_mem)
diff --git a/src/memos/mem_scheduler/base_scheduler.py b/src/memos/mem_scheduler/base_scheduler.py
index 4c9310cbb..5ab524128 100644
--- a/src/memos/mem_scheduler/base_scheduler.py
+++ b/src/memos/mem_scheduler/base_scheduler.py
@@ -964,6 +964,14 @@ def _message_consumer(self) -> None:
         # Original local queue logic
         while self._running:  # Use a running flag for graceful shutdown
             try:
+                # Check dispatcher thread pool status to avoid overloading
+                if self.enable_parallel_dispatch and self.dispatcher:
+                    running_tasks = self.dispatcher.get_running_task_count()
+                    if running_tasks >= self.dispatcher.max_workers:
+                        # Thread pool is full, wait and retry
+                        time.sleep(self._consume_interval)
+                        continue
+
                 # Get messages in batches based on consume_batch setting
 
                 messages = self.memos_message_queue.get_messages(batch_size=self.consume_batch)
diff --git a/src/memos/mem_scheduler/optimized_scheduler.py b/src/memos/mem_scheduler/optimized_scheduler.py
index 7007f8418..497d19ac6 100644
--- a/src/memos/mem_scheduler/optimized_scheduler.py
+++ b/src/memos/mem_scheduler/optimized_scheduler.py
@@ -43,10 +43,14 @@ def __init__(self, config: GeneralSchedulerConfig):
         self.session_counter = OrderedDict()
         self.max_session_history = 5
 
-        self.api_module = SchedulerAPIModule(
-            window_size=self.window_size,
-            history_memory_turns=self.history_memory_turns,
-        )
+        if self.config.use_redis_queue:
+            self.api_module = SchedulerAPIModule(
+                window_size=self.window_size,
+                history_memory_turns=self.history_memory_turns,
+            )
+        else:
+            self.api_module = None
+
         self.register_handlers(
             {
                 API_MIX_SEARCH_TASK_LABEL: self._api_mix_search_message_consumer,
@@ -104,7 +108,8 @@ def search_memories(
         target_session_id = search_req.session_id
         if not target_session_id:
             target_session_id = "default_session"
-        search_filter = {"session_id": search_req.session_id} if search_req.session_id else None
+        search_priority = {"session_id": search_req.session_id} if search_req.session_id else None
+        search_filter = search_req.filter
 
         # Create MemCube and perform search
         search_results = mem_cube.text_mem.search(
@@ -114,6 +119,7 @@ def search_memories(
             mode=mode,
             manual_close_internet=not search_req.internet_search,
             search_filter=search_filter,
+            search_priority=search_priority,
             info={
                 "user_id": search_req.user_id,
                 "session_id": target_session_id,
@@ -134,6 +140,22 @@ def mix_search_memories(
             f"Mix searching memories for user {search_req.user_id} with query: {search_req.query}"
         )
 
+        if not self.config.use_redis_queue:
+            logger.warning(
+                "Redis queue is not enabled. Running in degraded mode: "
+                "FAST search only, no history memory reranking, no async updates."
+            )
+            memories = self.search_memories(
+                search_req=search_req,
+                user_context=user_context,
+                mem_cube=self.mem_cube,
+                mode=SearchMode.FAST,
+            )
+            return [
+                format_textual_memory_item(item, include_embedding=search_req.dedup == "sim")
+                for item in memories
+            ]
+
         # Get mem_cube for fast search
         target_session_id = search_req.session_id
         if not target_session_id:
diff --git a/src/memos/mem_scheduler/orm_modules/api_redis_model.py b/src/memos/mem_scheduler/orm_modules/api_redis_model.py
index 04cd7e833..546dcc956 100644
--- a/src/memos/mem_scheduler/orm_modules/api_redis_model.py
+++ b/src/memos/mem_scheduler/orm_modules/api_redis_model.py
@@ -428,7 +428,8 @@ def load_redis_engine_from_env(env_file_path: str | None = None) -> Any:
                 logger.info(f"Loaded environment variables from {env_file_path}")
             else:
                 logger.warning(
-                    f"Environment file not found: {env_file_path}, using current environment variables"
+                    f"Environment file not found: {env_file_path}, using current environment variables",
+                    stack_info=True,
                 )
         else:
             logger.info("Using current environment variables (no env_file_path provided)")
@@ -513,5 +514,5 @@ def load_redis_engine_from_env(env_file_path: str | None = None) -> Any:
 
         except Exception as e:
             error_msg = f"Failed to create Redis connection from environment variables: {e}"
-            logger.error(error_msg)
+            logger.error(error_msg, stack_info=True)
             raise DatabaseError(error_msg) from e