Execute inference throwing error: Google.Protobuf.Message.DecodeError: Error Parsing Message

Hello all,

What is the top-level directory of the model you are using /tensorflow/models/research/object_detection
Have I written custom code: No
OS Platform and Distribution: Linux 16.04 LTS
TensorFlow installed from Bazel
TensorFlow version 1.12.0-rc2
Bazel version N/A
CUDA/cuDNN version CUDA release 10.0, V10.0.130, cudNN 7.3.1
GPU model and memory GeForce GTX 980 Ti, 6Gb
Exact command to reproduce: Exact command see above

I am currently using the Tensorflow Object Detection API to train a new model and test it with the KITTI data (as they are provided in within the API).

What have I done?
First, I downloaded the pre-trained ResNet101 model (trained on Kitti data) from the model zoo and I ran the inference and everything worked as expected.

However, running the inference on a fine-tuned model, I obtain the following error:

  File "infer_detections.py", line 96, in <module>
    tf.app.run()
  File "/home/user/.local/lib/python3.5/site-packages/tensorflow/python/platform/app.py", line 125, in run
    _sys.exit(main(argv))
  File "infer_detections.py", line 74, in main
    image_tensor, FLAGS.inference_graph)
  File "/home/user/tensorflow/models/research/object_detection/inference/detection_inference.py", line 71, in build_inference_graph
    graph_def.MergeFromString(graph_content)
google.protobuf.message.DecodeError: Error parsing message

I use this command to do the inference:

python3.5 infer_detections.py --input_tfrecord_paths=/home/user/tensorflow/models/research/object_detection/data/kitti.record_val.tfrecord --output_tfrecord_path=/home/user/tensorflow/models/research/object_detection/OUTPUT/test/kitti_test.tfrecord --inference_graph=/home/user/tensorflow/models/research/object_detection/OUTPUT/model_12April/export/Servo/1555067137/saved_model.pb --discard_image_pixels

Does anybody know why this error appear? Could it be the case that the error is located within the structure of how the model is saved?
The downloaded pre-trained Resnet101 (trained on Kitti data) is organized in the following data structure

|-- faster_rcnn_resnet101_kitti_2018_01_28
    |-- saved_model
        |-- variables 
        |-- saved_model.pb
    |-- checkpoint
    |-- frozen_inference_graph.pb
    |-- model.ckpt.data-00000-of-00001
    |-- model.ckpt.index
    |-- model.ckpt.meta
    |--pipeline.config

However, the data folder that is created in my Output Folder of the training is organized in as follows:

|-- OutputFolder
    |-- eval_0
        |-- Eventfile
    |-- export
        |-- Servo 
            |-- 1555067137
                 |-- variables
                      |-- variables.data-00000-of-00001
                      |-- variables.index
                 |-- saved_model.pb
    |-- checkpoint 
    |--event File
    |-- graph.pbtxt
    |-- model.ckpt-1961.data-00000-of-00001
    |-- model.ckpt-1961.index
    |-- model.ckpt-1961.meta

Am I using the wrong pb file ? I do not see a frozen_inference_graph.pb file (or similar). Does anybody have a hint how I could solve this?

Thanks a lot in advance and kind regards