Solved by CedricLy in post #8 
              
              
                Hi can you try your code with the line: 
optimizer=optim.SGD(model.fc.parameters(), lr=learning_rate) 
The code seems totally legit and either this is the problem or one has to check the dataloader further. 
There is also the probability of this 
model.fc = new_fc_layers

assignment needs to be done…