Add new layer to model

I have a model that I trained on small data. Weight network I saved. Now I want to add a new layer to this model, how to do it? I tried to add a new layer with a new name, but I still have an error.
Error(s) in loading state_dict for Net: Missing key(s) in state_dict: “fc4.weight”, “fc4.bias”, “bn5.running_mean”, “bn5.running_var”.

Load your model using your_new_model.load_state_dict(your_old_state_dict, strict=False)