model_save method crashing python
Can you also post the model here? A link to colab would be nice.

If you cannot share the model (private architecture, private data, etc.), can you try to provide a minimal reproducible example? This is needed so the team can debug Hi @rejahn ,

Please submit minimal repro code snippet. We need details like callback code and MODEL_FOLDER you are using to check with dummy model. Making a small change in the `tensorflow/python/saved_model/nested_structure_coder.py`  [here](https://github.com/tensorflow/tensorflow/blob/4b2ee4534df8208ae3a6e87a6386427288ae6765/tensorflow/python/saved_model/nested_structure_coder.py#L195C1-L195C69) will solve the problem.

Change:
```encoded_dict.dict_value.fields[key].CopyFrom(encode_fn(value))```  
to  
```encoded_dict.dict_value.fields[str(key)].CopyFrom(encode_fn(value))```  

Do you guys have maybe an idea what the problem could be? What if you change `str` with `repr` in the suggested fix? Actually, that shouldn't matter, it's just a key in a dict. Changing `str` with `repr` works as well - I am able to save our subclassed model. What if you try `hash(key)` just before trying to insert into the dict? using `hash(key)`:

```
Traceback (most recent call last):
  File "/home/user/repos/drivan/model/train_model.py", line 141, in <module>
    tf.keras.models.save_model(model, MODEL_FOLDER)
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/keras/saving/saving_api.py", line 145, in save_model
    return legacy_sm_saving_lib.save_model(
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/keras/utils/traceback_utils.py", line 70, in error_handler
    raise e.with_traceback(filtered_tb) from None
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/tensorflow/python/saved_model/nested_structure_coder.py", line 199, in do_encode
    encoded_dict.dict_value.fields[hash(key)].CopyFrom(encode_fn(value))
TypeError: bad argument type for built-in operation
```
 Oh, no, I meant just printing it before. Something like

```python
print(hash(key))
encoded_dict.dict_value.fields[str(key)].CopyFrom(encode_fn(value))
```

(Using `str(key)` in the dict as we know that that doesn't crash) Sorry about the confusion. 

I am getting following:

```
-6062824253216937473
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-5821025861464018857
-6062824253216937473
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
1
2
4
8
16
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
-696857728539794345
``` So no crash if I understand correctly?

In this case, I think it would be nice if you can provide us with a minimal model architecture (I don't think we need training data, but some randomized input could work) that could reproduce the issue. I'm out of guesses for what could go wrong :( Hi @rejahn ,

It seems we may not able to help without model architecture. I just tried a dummy model with your provided details and its working fine as per attached [gist](https://colab.sandbox.google.com/gist/SuryanarayanaY/31ccc5609560d0ccf7e59f9aebca439f/62587.ipynb). 

Thanks!

 I will try to work on a minimal reproducible example. For now, I will close the issue and open again as soon as I have an example. Are you satisfied with the resolution of your issue?
<a href="https://docs.google.com/forms/d/e/1FAIpQLSfaP12TRhd9xSxjXZjcZFNXPGk4kc1-qMdv3gc6bEP90vY1ew/viewform?entry.85265664=Yes&entry.2137816233=https://github.com/tensorflow/tensorflow/issues/62587">Yes</a>
<a href="https://docs.google.com/forms/d/e/1FAIpQLSfaP12TRhd9xSxjXZjcZFNXPGk4kc1-qMdv3gc6bEP90vY1ew/viewform?entry.85265664=No&entry.2137816233=https://github.com/tensorflow/tensorflow/issues/62587">No</a>

### Issue type

Bug

### Have you reproduced the bug with TensorFlow Nightly?

Yes

### Source

binary

### TensorFlow version

tf 2.12.1

### Custom code

Yes

### OS platform and distribution

Linux Ubuntu 20.04

### Mobile device

_No response_

### Python version

3.8

### Bazel version

_No response_

### GCC/compiler version

_No response_

### CUDA/cuDNN version

11.8/8.6

### GPU model and memory

NVIDIA Quadro P3200 6GB

### Current behavior?

I am currently having problems to save a model. After the training is completed, python crashes when calling [save_model](https://www.tensorflow.org/api_docs/python/tf/keras/saving/save_model) or creating a [ModelCheckpoint](https://www.tensorflow.org/api_docs/python/tf/keras/callbacks/ModelCheckpoint)

### Standalone code to reproduce the issue

```shell
### Training: ###
history = model.fit(train_data, validation_data=val_data,
                    epochs=EPOCHS, callbacks=callbacks)
print("finished fitting model")


# Saving model:
if not os.path.exists(MODEL_FOLDER):
    print("path doesn't exist")
    os.makedirs(MODEL_FOLDER)

tf.keras.models.save_model(model, MODEL_FOLDER, save_format='tf')
print("Model has been saved at" + MODEL_FOLDER)
```


### Relevant log output

```shell
Epoch 1/2
[ Warnings...]
210/210 [==============================] - ETA: 0s - loss: 0.4397     
Epoch 1: val_loss did not improve from 0.10000
210/210 [==============================] - 53s 131ms/step - loss: 0.4397 - val_loss: 0.2221
Epoch 2/2
210/210 [==============================] - ETA: 0s - loss: 0.1960  
Epoch 2: val_loss did not improve from 0.10000
210/210 [==============================] - 27s 125ms/step - loss: 0.1960 - val_loss: 0.1421
finished fitting model
WARNING:absl:Found untraced functions such as _jit_compiled_convolution_op, _jit_compiled_convolution_op, _jit_compiled_convolution_op, _jit_compiled_convolution_op, _jit_compiled_convolution_op while saving (showing 5 of 68). These functions will not be directly callable after loading.
Traceback (most recent call last):
  File "/home/user/repos/drivan/model/train_model.py", line 147, in <module>
    tf.keras.models.save_model(model, MODEL_FOLDER, save_format='tf')
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/keras/saving/saving_api.py", line 145, in save_model
    return legacy_sm_saving_lib.save_model(
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/keras/utils/traceback_utils.py", line 70, in error_handler
    raise e.with_traceback(filtered_tb) from None
  File "/home/user/repos/drivan/.venv/lib/python3.8/site-packages/tensorflow/python/saved_model/nested_structure_coder.py", line 196, in do_encode
    encoded_dict.dict_value.fields[key].CopyFrom(encode_fn(value))
TypeError: bad argument type for built-in operation
```
