onnx.onnx_cpp2py_export.checker.ValidationError: convolution_W in initializer but not in graph input

Describe the bug

convert from caffe model to tensorflow model

To Reproduce

Successfully convert from caffe to coreml to onnx using caffe2onnx When using onnx2tensorflow, i got the error:

Traceback (most recent call last):
  File "convert_caffe2onnx2tf.py", line 36, in <module>
    tf_exp = prepare(onnx_model)  # prepare tf representation
  File "/data6/TF_quant/onnx-tensorflow/onnx_tf/backend.py", line 62, in prepare
    super(TensorflowBackend, cls).prepare(model, device, **kwargs)
  File "/data5/workshop/anaconda3/lib/python3.6/site-packages/onnx/backend/base.py", line 74, in prepare
    onnx.checker.check_model(model)
  File "/data5/workshop/anaconda3/lib/python3.6/site-packages/onnx/checker.py", line 93, in check_model
    C.check_model(model.SerializeToString())
onnx.onnx_cpp2py_export.checker.ValidationError: convolution_W in initializer but not in graph input

My python code is:

import coremltools
import onnxmltools
import onnx
import warnings
from onnx_tf.backend import prepare

# Update your input name and path for your caffe model
proto_file = './mobilenet_v2_nobn.prototxt' 
input_caffe_path = './mobilenet_v2_nobn.caffemodel'

# Update the output name and path for intermediate coreml model, or leave as is
output_coreml_model = './mobilenet_v2_nobn.mlmodel'

# Change this path to the output name and path for the onnx model
output_onnx_model = './mobilenet_v2_nobn.onnx'

pb_output_path = './mobilenet_v2_nobn.pb'

# Convert Caffe model to CoreML 
coreml_model = coremltools.converters.caffe.convert((input_caffe_path, proto_file))

# Save CoreML model
coreml_model.save(output_coreml_model)

# Load a Core ML model
coreml_model = coremltools.utils.load_spec(output_coreml_model)

# Convert the Core ML model into ONNX
onnx_model = onnxmltools.convert_coreml(coreml_model)

# Save as protobuf
onnxmltools.utils.save_model(onnx_model, output_onnx_model)

onnx_model = onnx.load(output_onnx_model)  # load onnx model

tf_exp = prepare(onnx_model)  # prepare tf representation

tf_exp.export_graph(pb_output_path)  # export the model

ONNX model file Mobilenet v2 model: https://drive.google.com/drive/folders/1Q7k5iLxa0VYoGueG1mhD6plV2TV4Zlp_?usp=sharing

Python, ONNX, ONNX-TF, Tensorflow version

This section can be obtained by running get_version.py from util folder.

Python version: 3.6.10
ONNX version: 1.7.0
ONNX-TF version: 1.6.0
Tensorflow version: 2.0.0

Additional context

The caffemodel with Batchnorm works, but got error after merge_bn.

onnx / onnx-tensorflow

onnx.onnx_cpp2py_export.checker.ValidationError: convolution_W in initializer but not in graph input #740