Solved by L-Reichardt in post #2 
              
              
                Haven’t found much for conv2d_prepack, but have you tried passing a tuple as stride? 
self._packed_params = torch.ops.quantized.conv2d_prepack(w, b, (self.stride, self.stride), self.padding, self.dilation, self.groups)

If that is the issue, you might need to pass padding as a tuple as well.