How to load the Keras model with custom layers from .h5 file correctly?

Actually I don't think you can load this model.

The most likely issue is that you did not implement the get_config() method in your layer. This method returns a dictionary of configuration values that should be saved:

def get_config(self):
    config = {'pool_size': self.pool_size,
              'axis': self.axis}
    base_config = super(MyMeanPooling, self).get_config()
    return dict(list(base_config.items()) + list(config.items()))

You have to retrain the model after adding this method to your layer, as the previously saved model does not have the configuration for this layer saved into it. This is why you cannot load it, it requires retraining after making this change.

From the answer of "LiamHe commented on Sep 27, 2017" on the following issue: https://github.com/keras-team/keras/issues/4871.

I met the same problem today : ** TypeError: init() missing 1 required positional arguments**. Here is how I solve the problem : (Keras 2.0.2)

1. Give the positional arguments of the layer with some default values
2. Override get_config function to the layer with some thing like

def get_config(self):
    config = super().get_config()
    config['pool_size'] = # say self._pool_size  if you store the argument in __init__
    return config

3. Add layer class to custom_objects when you are loading model.