Hi Aleena,
When asking for help, it really helps us help you if you can try to narrow down what the problem is. And exactly what you’re doing. You haven’t posted any code building or using this model, and it’s possible that that’s where the problem is.
Also it’s hard to tell if these are copy-paste errors but I see some suspicious things:



 Aleena_Suhail:

def bn_act(x, act=True): 
  x = keras.layers.BatchNormalization()(x)
  if act == True:
    x = keras.layers.Activation("relu")(x)
    return x



If act is False this function returns None.



 Aleena_Suhail:

def ResUNet():
    f = [16, 32, 64, 128, 256]
    ...
    model = keras.models.Model(inputs, outputs)
    return model
    
    model.summary()



That model.summary is after the return, so it will never get run.