Hi @ptrblck,
Thanks a lot for the help! Now my model is training. Here are the changes I made after your last reply:

changed model.classifier to model.fc (Is this information included in pytorch documentation?)

fc = nn.Sequential(OrderedDict([
                          ('fc1', nn.Linear(2048, 500)),
                          ('relu', nn.ReLU()),
                          ('fc2', nn.Linear(500, 2)),
                          ('output', nn.LogSoftmax(dim=1))
                          ]))
    
model.fc = fc



Changed my criterion from nn.NLLLoss() to nn.CrossEntropyLoss() (I don’t think this is relevant but I’ll check loss documentation)


Changed loss = criterion(logps, labels) to loss = criterion(logps[0], labels)


First and the third changes according to your suggestions helped to start training the network.