Traceback (most recent call last):


 "<ipython-input-3-944ebf5453bb>", line 4, in <module>

raise ValueError('failed') from e
ValueError: failed

Traceback (most recent call last):


 "/home/aci-user/venv36/bin/ludwig", line 11, in <module>

sys.exit(main())


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/cli.py", line 108, in main

CLI()


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/cli.py", line 64, in __init__

getattr(self, args.command)()


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/cli.py", line 74, in train

train.cli(sys.argv[2:])


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/train.py", line 785, in cli

full_train(**vars(args))


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/train.py", line 336, in full_train

debug=debug


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/train.py", line 483, in train

debug=debug


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/models/model.py", line 113, in __init__

**kwargs


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/models/model.py", line 187, in __build

is_training=self.is_training


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/models/outputs.py", line 46, in build_outputs

**kwargs


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/models/outputs.py", line 96, in build_single_output

**kwargs


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/features/base_feature.py", line 314, in concat_dependencies_and_build_output

**kwargs


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/features/text_feature.py", line 291, in build_output

kwarg=kwargs


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/features/sequence_feature.py", line 314, in build_sequence_output

class_biases


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/features/sequence_feature.py", line 529, in sequence_loss

self.num_classes


 "/home/aci-user/venv36/lib64/python3.6/site-packages/ludwig/models/modules/loss_modules.py", line 239, in sequence_sampled_softmax_cross_entropy

raise ValueError('Unsupported sampler {}'.format(loss['sampler']))
ValueError: Unsupported sampler None
