I have an QAT quantized_model which has no problem to run:
quantized_model.eval()
_ = quantized_model(torch.rand(1,3,300,300))

and it also can be traced successfuly:
trace_model = torch.jit.trace(quantized_model, torch.Tensor(1,3,300,300))

but when I tried to run the trace_model as below:
trace_model.eval()
 _ = trace_model(torch.rand(1,3,300,300))

I encountered the following error message:
  _ = trace_model(torch.rand(1,3,300,300))
  File "/home/paul/rknn2/lib/python3.6/site-packages/torch/nn/modules/module.py", line 722, in _call_impl
    result = self.forward(*input, **kwargs)
RuntimeError: The following operation failed in the TorchScript interpreter.
Traceback of TorchScript (most recent call last):
RuntimeError: The following operation failed in the TorchScript interpreter.
Traceback of TorchScript (most recent call last):
  File "<string>", line 63, in <foward op>
                       dilation: List[int],
                       ceil_mode: bool):
            output, indices = torch.max_pool2d_with_indices(self, kernel_size, stride, padding, dilation, ceil_mode)
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <--- HERE
            def backward(grad_output):
                grad_self = torch.max_pool2d_with_indices_backward(grad_output, self, kernel_size, stride, padding, dilation, ceil_mode, indices)
RuntimeError: Could not run 'aten::max_pool2d_with_indices' with arguments from the 'QuantizedCPU' backend. 'aten::max_pool2d_with_indices' is only available for these backends: [CPU, CUDA, Named, Autograd, Profiler, Tracer].

What am I missing? How can I fix this error? Thank you for your help.