diff --git a/server/sio/MMVC_Namespace.py b/server/sio/MMVC_Namespace.py
index 39154f32..6a16bc4e 100644
--- a/server/sio/MMVC_Namespace.py
+++ b/server/sio/MMVC_Namespace.py
@@ -43,7 +43,6 @@ class MMVC_Namespace(socketio.AsyncNamespace):
 
     async def on_request_message(self, sid, msg):
         self.sid = sid
-        await self.asynctest("on req")
         timestamp = int(msg[0])
         data = msg[1]
         if isinstance(data, str):
diff --git a/server/voice_changer/RVC/ModelSlotGenerator.py b/server/voice_changer/RVC/ModelSlotGenerator.py
index f13473cd..03c0c28b 100644
--- a/server/voice_changer/RVC/ModelSlotGenerator.py
+++ b/server/voice_changer/RVC/ModelSlotGenerator.py
@@ -8,47 +8,51 @@ import os
 
 
 def generateModelSlot(slotDir: str):
-    modelSlot = ModelSlot()
-    if os.path.exists(slotDir) is False:
+    try:
+        modelSlot = ModelSlot()
+        if os.path.exists(slotDir) is False:
+            return modelSlot
+        paramFile = os.path.join(slotDir, "params.json")
+        with open(paramFile, "r") as f:
+            params = json.load(f)
+
+        modelSlot.modelFile = os.path.join(
+            slotDir, os.path.basename(params["files"]["rvcModel"])
+        )
+        if "rvcFeature" in params["files"]:
+            modelSlot.featureFile = os.path.join(
+                slotDir, os.path.basename(params["files"]["rvcFeature"])
+            )
+        else:
+            modelSlot.featureFile = None
+        if "rvcIndex" in params["files"]:
+            modelSlot.indexFile = os.path.join(
+                slotDir, os.path.basename(params["files"]["rvcIndex"])
+            )
+        else:
+            modelSlot.indexFile = None
+
+        modelSlot.defaultTune = params["defaultTune"] if "defaultTune" in params else 0
+        modelSlot.defaultIndexRatio = (
+            params["defaultIndexRatio"] if "defaultIndexRatio" in params else 0
+        )
+        modelSlot.name = params["name"] if "name" in params else None
+        modelSlot.description = params["description"] if "description" in params else None
+        modelSlot.credit = params["credit"] if "credit" in params else None
+        modelSlot.termsOfUseUrl = (
+            params["termsOfUseUrl"] if "termsOfUseUrl" in params else None
+        )
+
+        modelSlot.isONNX = modelSlot.modelFile.endswith(".onnx")
+
+        if modelSlot.isONNX:
+            _setInfoByONNX(modelSlot)
+        else:
+            _setInfoByPytorch(modelSlot)
         return modelSlot
-    paramFile = os.path.join(slotDir, "params.json")
-    with open(paramFile, "r") as f:
-        params = json.load(f)
-
-    modelSlot.modelFile = os.path.join(
-        slotDir, os.path.basename(params["files"]["rvcModel"])
-    )
-    if "rvcFeature" in params["files"]:
-        modelSlot.featureFile = os.path.join(
-            slotDir, os.path.basename(params["files"]["rvcFeature"])
-        )
-    else:
-        modelSlot.featureFile = None
-    if "rvcIndex" in params["files"]:
-        modelSlot.indexFile = os.path.join(
-            slotDir, os.path.basename(params["files"]["rvcIndex"])
-        )
-    else:
-        modelSlot.indexFile = None
-
-    modelSlot.defaultTune = params["defaultTune"] if "defaultTune" in params else 0
-    modelSlot.defaultIndexRatio = (
-        params["defaultIndexRatio"] if "defaultIndexRatio" in params else 0
-    )
-    modelSlot.name = params["name"] if "name" in params else None
-    modelSlot.description = params["description"] if "description" in params else None
-    modelSlot.credit = params["credit"] if "credit" in params else None
-    modelSlot.termsOfUseUrl = (
-        params["termsOfUseUrl"] if "termsOfUseUrl" in params else None
-    )
-
-    modelSlot.isONNX = modelSlot.modelFile.endswith(".onnx")
-
-    if modelSlot.isONNX:
-        _setInfoByONNX(modelSlot)
-    else:
-        _setInfoByPytorch(modelSlot)
-    return modelSlot
+    except Exception as e:
+        print(f"[Voice Changer] faild to generate slot: {e}")
+        return ModelSlot()
 
 
 def _setInfoByPytorch(slot: ModelSlot):
diff --git a/server/voice_changer/VoiceChanger.py b/server/voice_changer/VoiceChanger.py
index dba1832a..413aeb36 100755
--- a/server/voice_changer/VoiceChanger.py
+++ b/server/voice_changer/VoiceChanger.py
@@ -92,7 +92,7 @@ class VoiceChangerSettings:
 
 class VoiceChanger:
     settings: VoiceChangerSettings
-    voiceChanger: VoiceChangerModel
+    voiceChanger: VoiceChangerModel | None = None
     ioRecorder: IORecorder
     sola_buffer: AudioInOut
     namespace: socketio.AsyncNamespace | None = None
@@ -142,6 +142,7 @@ class VoiceChanger:
             if (
                 vc.settings.serverAudioStated == 0
                 or vc.settings.serverInputDeviceId == -1
+                or vc.voiceChanger is None
             ):
                 vc.settings.inputSampleRate = 48000
                 time.sleep(2)
@@ -270,7 +271,7 @@ class VoiceChanger:
 
     def switchModelType(self, modelType: ModelType):
         try:
-            if hasattr(self, "voiceChanger") and self.voiceChanger is not None:
+            if self.voiceChanger is not None:
                 # return {"status": "ERROR", "msg": "vc is already selected. currently re-select is not implemented"}
                 del self.voiceChanger
                 self.voiceChanger = None
@@ -320,6 +321,8 @@ class VoiceChanger:
 
     def loadModel(self, props: LoadModelParams):
         try:
+            if self.voiceChanger is None:
+                raise RuntimeError("Voice Changer is not selected.")
             return self.voiceChanger.loadModel(props)
         except Exception as e:
             print(traceback.format_exc())
@@ -328,7 +331,7 @@ class VoiceChanger:
 
     def get_info(self):
         data = asdict(self.settings)
-        if hasattr(self, "voiceChanger"):
+        if self.voiceChanger is not None:
             data.update(self.voiceChanger.get_info())
         return data
 
@@ -336,6 +339,10 @@ class VoiceChanger:
         return self.settings.performance
 
     def update_settings(self, key: str, val: Any):
+        if self.voiceChanger is None:
+            print("[Voice Changer] Voice Changer is not selected.")
+            return
+
         if key in self.settings.intData:
             setattr(self.settings, key, int(val))
             if key == "crossFadeOffsetRate" or key == "crossFadeEndRate":
@@ -359,12 +366,9 @@ class VoiceChanger:
         elif key in self.settings.strData:
             setattr(self.settings, key, str(val))
         else:
-            if hasattr(self, "voiceChanger"):
-                ret = self.voiceChanger.update_settings(key, val)
-                if ret is False:
-                    print(f"{key} is not mutable variable or unknown variable!")
-            else:
-                print("voice changer is not initialized!")
+            ret = self.voiceChanger.update_settings(key, val)
+            if ret is False:
+                print(f"{key} is not mutable variable or unknown variable!")
         return self.get_info()
 
     def _generate_strength(self, crossfadeSize: int):
@@ -422,6 +426,9 @@ class VoiceChanger:
         self, receivedData: AudioInOut
     ) -> tuple[AudioInOut, list[Union[int, float]]]:
         try:
+            if self.voiceChanger is None:
+                raise RuntimeError("Voice Changer is not selected.")
+
             processing_sampling_rate = self.voiceChanger.get_processing_sampling_rate()
 
             # 前処理
@@ -571,10 +578,16 @@ class VoiceChanger:
         ##############
 
     def merge_models(self, request: str):
+        if self.voiceChanger is None:
+            print("[Voice Changer] Voice Changer is not selected.")
+            return
         self.voiceChanger.merge_models(request)
         return self.get_info()
 
     def update_model_default(self):
+        if self.voiceChanger is None:
+            print("[Voice Changer] Voice Changer is not selected.")
+            return
         self.voiceChanger.update_model_default()
         return self.get_info()