diff --git a/paddlespeech/server/engine/asr/online/asr_engine.py b/paddlespeech/server/engine/asr/online/asr_engine.py
index 0c5e4586..ec19aaf1 100644
--- a/paddlespeech/server/engine/asr/online/asr_engine.py
+++ b/paddlespeech/server/engine/asr/online/asr_engine.py
@@ -794,7 +794,7 @@ class ASRServerExecutor(ASRExecutor):
                 # update num_decoding_left_chunks
                 if num_decoding_left_chunks:
                     self.config.decode.num_decoding_left_chunks = num_decoding_left_chunks
-                    assert self.config.decode.num_decoding_left_chunks == -1 or self.config.decode.num_decoding_left_chunks >= 0, f"num_decoding_left_chunks should be -1 or >=0"
+                    assert self.config.decode.num_decoding_left_chunks == -1 or self.config.decode.num_decoding_left_chunks >= 0, "num_decoding_left_chunks should be -1 or >=0"
                 # we only support ctc_prefix_beam_search and attention_rescoring dedoding method
                 # Generally we set the decoding_method to attention_rescoring
                 if self.config.decode.decoding_method not in [
diff --git a/paddlespeech/server/ws/asr_api.py b/paddlespeech/server/ws/asr_api.py
index 23609b41..ae1c8831 100644
--- a/paddlespeech/server/ws/asr_api.py
+++ b/paddlespeech/server/ws/asr_api.py
@@ -92,7 +92,7 @@ async def websocket_endpoint(websocket: WebSocket):
                 else:
                     resp = {"status": "ok", "message": "no valid json data"}
                     await websocket.send_json(resp)
-                    
+
             elif "bytes" in message:
                 # bytes for the pcm data
                 message = message["bytes"]