I have a trouble because come from difference version

I had train yolov3 use pytorch 0.4,but yesterday I update my pytorch version to 1.0. So a error come out, this is error message.
cannot perform reduction function max on tensor with no elements because the operation does not have an identity.

I think this code is the bad code for version 1.0.
loss_cls = (1 / nB) * self.ce_loss(pred_cls[mask], torch.argmax(tcls[mask], 1)).

Is there any one help me

I am sorry .It is my fault. Please do not reply this topic.

How did you solve it? @mshmoon