No grad accumulator for a saved leaf!

How do you get this error? Do you still use .data?
Do you always have a bias? Does it require gradients? Do you return gradient in the backward for it all the time?

What is the other way other than using *.data to make weights for self.conv2 to be equal to weights of self.conv1?

Is there a reason why they are two different Tensors? If you just want them to have the same weight Tensor, just do that in the init by creating MyConv with self.conv1.weight or by passing this to your custom forward directly.