Error saving Keras optimizer, TensorFlow 2.0

[OverLordGoldDragon]

Related, minimal reproducible example below. Opened a PR, but doesn't fix this problem.

---

DOESN'T WORK:

from tensorflow.python.keras.layers import Input, Dense
from tensorflow.python.keras.models import Model
from tensorflow.python.keras.optimizers import Nadam # [3]

import numpy as np
ipt = Input(shape=(4,))
out = Dense(1, activation='sigmoid')(ipt)

model = Model(ipt, out)
model.compile(optimizer=Nadam(lr=1e-4), loss='binary_crossentropy')

X = np.random.randn(32,4)
Y = np.random.randint(0,2,(32,1))
model.train_on_batch(X,Y)

modelpath = "folder/model.h5"
model.save(modelpath)

---

WORKS: remove .python from above's imports, OR, model.save(.., include_optimizer=False). Also works if .python is removed only from import # [3].

---

Full error trace:

  File "<ipython-input-1-fedd4f332165>", line 23, in <module>
    model.save(modelpath)

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\tensorflow_core\python\keras\engine\network.py", line 975, in save
    signatures, options)

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\tensorflow_core\python\keras\saving\save.py", line 112, in save_model
    model, filepath, overwrite, include_optimizer)

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\tensorflow_core\python\keras\saving\hdf5_format.py", line 115, in save_model_to_hdf5
    save_optimizer_weights_to_hdf5_group(f, model.optimizer)

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\tensorflow_core\python\keras\saving\hdf5_format.py", line 587, in save_optimizer_weights_to_hdf5_group
    name, val.shape, dtype=val.dtype)

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\h5py\_hl\group.py", line 139, in create_dataset
    self[name] = dset

  File "D:\Anaconda\envs\tf2_env\lib\site-packages\h5py\_hl\group.py", line 371, in __setitem__
    h5o.link(obj.id, self.id, name, lcpl=lcpl, lapl=self._lapl)

  File "h5py\_objects.pyx", line 54, in h5py._objects.with_phil.wrapper

  File "h5py\_objects.pyx", line 55, in h5py._objects.with_phil.wrapper

  File "h5py\h5o.pyx", line 202, in h5py.h5o.link

RuntimeError: Unable to create link (name already exists)

[rmothukuru]

@OverLordGoldDragon,
When I tried reproducing your error, I got a different error, as shown below.

ValueError: Tried to convert 'y' to a tensor and failed. Error: None values not supported.

Please find the Gist.

Can you please help me to reproduce the issue. Thanks!

[OverLordGoldDragon]

@rmothukuru Right, that's another problem for which I started a Pull Request - you can implement the fix manually in the meantime.

[OverLordGoldDragon]

Solved. TL;DR - .python isn't meant to be used for this purpose.