Issue 1:
System information

Have I written custom code (as opposed to using a stock example script provided in TensorFlow): Yes

OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Windows 10

TensorFlow installed from (source or binary): binary (pip)

TensorFlow version (use command below): 1.5.0-dev20171210 (nightly from today)

Python version: 3.6.2

ArgMax crashes with no gradient error. I had a working version before I made slight adjustments to my code. I am very confused how this error can happen.

Stacktrace:

File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\learn\python\learn\learn_runner.py", line 46, in _execute_schedule
return task()
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\learn\python\learn\experiment.py", line 377, in train
saving_listeners=self._saving_listeners)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\learn\python\learn\experiment.py", line 824, in _call_train
saving_listeners=saving_listeners)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\python\estimator\estimator.py", line 314, in train
loss = self._train_model(input_fn, hooks, saving_listeners)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\python\estimator\estimator.py", line 743, in _train_model
features, labels, model_fn_lib.ModeKeys.TRAIN, self.config)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\python\estimator\estimator.py", line 725, in _call_model_fn
model_fn_results = self._model_fn(features=features, **kwargs)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\gan\python\estimator\python\gan_estimator_impl.py", line 162, in _model_fn
add_summaries)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\gan\python\estimator\python\gan_estimator_impl.py", line 235, in _gan_model_fn
labels=None)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\gan\python\estimator\python\head_impl.py", line 189, in create_estimator_spec
self._discriminator_optimizer)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\gan\python\train.py", line 540, in gan_train_ops
**kwargs)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\contrib\training\python\training\training.py", line 447, in create_train_op
colocate_gradients_with_ops=colocate_gradients_with_ops)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\python\training\optimizer.py", line 456, in compute_gradients
colocate_gradients_with_ops=colocate_gradients_with_ops)
File "C:\Development\Tools\miniconda\envs\mpgan-nightly\lib\site-packages\tensorflow\python\ops\gradients_impl.py", line 581, in gradients
(op.name, op.type))
LookupError: No gradient defined for operation 'Generator/cond/generator/generator/while/BasicDecoderStep/TrainingHelperSample/ArgMax' (op type: ArgMax)

Issue 2:
LookupError: No gradient defined for operation 'Argmax' (op type: Argmax)