Solved by Mahmoud_Abdelkhalek in post #2 
              
              
                You could step into the forward pass like this: 
x = torch.randn((1,3,28,28))
y = pretrained_model(x)

Make sure you step into y = pretrained_model(x) using pdb. Eventually, you will reach the forward method of the pre-trained model’s class, after which you can probe the different tensor shapes. 
Al…