How to fix “TOCO failed. Check failed: dim >= 1 (0 vs. 1)” error while converting a frozen graph into a tensorflow_lite model

Question

I have trained an object detection model. Now I'm trying to speed it up for inference using quantization provided by Tensorflow Lite graph converter . But when I call the tf.lite.TFLiteConverter.from_frozen_graph method, I am running into an error.

I have also found a similar, unanswered question asked almost a year ago and I was wondering if TFLite's support has improved now.

Here is what I'm calling:

converter = tf.lite.TFLiteConverter.from_frozen_graph(
    model_path,
    input_arrays = ['input_1'],
    output_arrays = [
        'filtered_detections/map/TensorArrayStack/TensorArrayGatherV3',
        'filtered_detections/map/TensorArrayStack_1/TensorArrayGatherV3',
        'filtered_detections/map/TensorArrayStack_2/TensorArrayGatherV3'
        ],
    input_shapes = { 
        'input_1': [None, 300, 300, 3]
        }
    )
converter.post_training_quantize = True
tflite_quantized_model = converter.convert()

EDIT: I have also tried different parameter values for input_1 like [1, 300, 300, 3] etc. I have even left out the input_shapes parameter but then it throws another error: None is allowed only in 1st dimension. Other dimensions can not be null None is allowed only in 1st dimension. Other dimensions can not be null

Here are the error logs:

File "lib/python3.6/site-packages/tensorflow/lite/python/lite.py", line 500, in convert
    **converter_kwargs)
  File "lib/python3.6/site-packages/tensorflow/lite/python/convert.py", line 442, in toco_convert_impl
    input_data.SerializeToString())
  File "lib/python3.6/site-packages/tensorflow/lite/python/convert.py", line 205, in toco_convert_protos
    "TOCO failed. See console for info.\n%s\n%s\n" % (stdout, stderr))
tensorflow.lite.python.convert.ConverterError: TOCO failed. See console for info.
2019-02-06 18:38:40.906888: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: Enter
2019-02-06 18:38:40.915666: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: Enter
2019-02-06 18:38:40.917286: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: Size
2019-02-06 18:38:40.917308: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: Size
...
...
2019-02-06 18:38:40.918758: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: TensorArrayWriteV3
2019-02-06 18:38:40.918783: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: TensorArrayWriteV3
2019-02-06 18:38:40.918796: I tensorflow/lite/toco/import_tensorflow.cc:1332] Converting unsupported operation: TensorArrayWriteV3
2019-02-06 18:38:40.935936: I tensorflow/lite/toco/graph_transformations/graph_transformations.cc:39] Before Removing unused ops: 952 operators, 1408 arrays (0 quantized)
2019-02-06 18:38:40.955338: I tensorflow/lite/toco/graph_transformations/graph_transformations.cc:39] Before general graph transformations: 952 operators, 1408 arrays (0 quantized)
2019-02-06 18:38:41.234167: I tensorflow/lite/toco/graph_transformations/graph_transformations.cc:39] After general graph transformations pass 1: 396 operators, 708 arrays (0 quantized)
2019-02-06 18:38:41.242773: I tensorflow/lite/toco/graph_transformations/graph_transformations.cc:39] Before Group bidirectional sequence lstm/rnn: 396 operators, 708 arrays (0 quantized)
2019-02-06 18:38:41.249476: I tensorflow/lite/toco/graph_transformations/graph_transformations.cc:39] Before dequantization graph transformations: 396 operators, 708 arrays (0 quantized)
2019-02-06 18:38:41.262130: F tensorflow/lite/toco/tooling_util.cc:633] Check failed: dim >= 1 (0 vs. 1)
Fatal Python error: Aborted

Current thread 0x00007f4930238740 (most recent call first):
  File "lib/python3.6/site-packages/tensorflow/lite/toco/python/toco_from_protos.py", line 33 in execute
  File "lib/python3.6/site-packages/absl/app.py", line 251 in _run_main
  File "lib/python3.6/site-packages/absl/app.py", line 300 in run
  File "lib/python3.6/site-packages/tensorflow/python/platform/app.py", line 40 in run
  File "lib/python3.6/site-packages/tensorflow/lite/toco/python/toco_from_protos.py", line 59 in main
  File "bin/toco_from_protos", line 11 in <module>
Aborted (core dumped)

Answer 1

The problem is in existing unsupported tensorflow ops by tflite converter:

Converting unsupported operation: Enter

Converting unsupported operation: Size

Converting unsupported operation: TensorArrayWriteV3

Try to find a way to not use this operations in original tensorflow graph.

Refer this link which gives information on TFLite supported operations.