Builder.build_cuda_engine(network) silently returns None


A clear and concise description of the bug or issue.


TensorRT Version: (installed in virtualenv with nvidia-tensorrt)
GPU Type: 2070
Nvidia Driver Version: 460
CUDA Version: 11.0
CUDNN Version:
Operating System + Version: Ubuntu 18.04
**Python Version **: 3.8.8
**PyTorch Version **: 1.7.1

Relevant Files

I am attempting to export and run as a TRT model efficientnet_b2 from this repo:

I export like:
output = “my_tf_3.onnx”

    import geffnet
    import onnx
    model = geffnet.create_model(
    DEVICE = torch.device("cuda")
    example_input = torch.randn(1, 3, 256, 256).to(DEVICE)
    input_names = ["input0"]
    output_names = ["output0"]
    torch.onnx.export(model, example_input, output, verbose=False,
                      input_names=input_names, output_names=output_names,

    print("==> Loading and checking exported model from '{}'".format(output))
    onnx_model = onnx.load(output)
    onnx.checker.check_model(onnx_model)  # assuming throw on error
    print("==> Passed")  

A netron diagram of the exported ONNX:

the exported ONNX:
my_tf_3.onnx (29.3 MB)

I try to run as a TRT engine:

import pycuda.driver as cuda
import pycuda.autoinit
import numpy as np
import tensorrt as trt

TRT_LOGGER = trt.Logger()

def build_engine(onnx_file_path):
    builder = trt.Builder(TRT_LOGGER)
    network = builder.create_network()
    parser = trt.OnnxParser(network, TRT_LOGGER)

    builder.max_workspace_size = 1 << 30
    builder.max_batch_size = 1

    # parse ONNX
    with open(onnx_file_path, 'rb') as model:
        print('Beginning ONNX file parsing')
    print('Completed parsing of ONNX file')

    # generate TensorRT engine optimized for the target platform
    print('Building an engine...')
    engine = builder.build_cuda_engine(network)
    context = engine.create_execution_context()
    print("Completed creating Engine")

    return engine, context

engine, context = build_engine("/home/luke/projects/traffic_light_classifier/my_tf_3.onnx")

And I get the error:

 30     print('Building an engine...')
 31     engine = builder.build_cuda_engine(network)
---> 32     context = engine.create_execution_context()
 33     print("Completed creating Engine")

AttributeError: 'NoneType' object has no attribute 'create_execution_context'

I’m not even really sure how to begin debugging this, any ideas?

1 Like

Hi @lukee2ni6,

Looks like engine building is failing. Could you please share complete logs for better debugging.

You can also try generating serialized engine quickly using trtexec command

Thank you.

Same problem for me, it works with CLI tetexec but not in python… I got a silent None from builder.build_serialized_network(network, config)

@trkodpd Hey, I have a similar issue. I have also created this post in case you want to give a follow up.

Would you mind telling me what procedure you followed to run the trtexec script from Nvidia?