Solved by InnovArul in post #2 
              
              
                Use the parameter strict=False with big_model.load_state_dict(). 
i.e.,  big_model.load_state_dict(torch.load('file.pth'), strict=False). 
import torch
from torch import nn
from torch.autograd import Variable, grad

#define network weights and input
class small_model(nn.Module):
    def __init__(sel…