Convert_graph_to_onnx doesn't meet UnicodeDecodeError

i want to convert dialogpt model to onnx model, this is my all code:

from transformers.convert_graph_to_onnx import convert
convert(framework="pt", model="DialoGPT-medium/pytorch_model.bin", output=Path("onnx/bert-base-chinese.onnx"), opset=7)

and i meet error:
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 64: invalid start byte
how can i fix this?