Getting an error when modifying the faster_rcnn model to add inception_v3 backbone model

I was following this tutorial Modifying the model to add a different backbone. When I replace the mobilenet_v2 model with inception_v3, the code does not work and gives the following error:

  File "/home/gpu-user/projects/building-outline-detection/src/models/faster_rcnn/vision/engine.py", line 46, in train_one_epoch
    loss_dict = model(images, targets)
  File "/home/gpu-user/miniconda3/envs/faster_rcnn/lib/python3.8/site-packages/torch/nn/modules/module.py", line 727, in _call_impl
    result = self.forward(*input, **kwargs)
  File "/home/gpu-user/miniconda3/envs/faster_rcnn/lib/python3.8/site-packages/torchvision/models/detection/generalized_rcnn.py", line 99, in forward
    proposals, proposal_losses = self.rpn(images, features, targets)
  File "/home/gpu-user/miniconda3/envs/faster_rcnn/lib/python3.8/site-packages/torch/nn/modules/module.py", line 727, in _call_impl
    result = self.forward(*input, **kwargs)
  File "/home/gpu-user/miniconda3/envs/faster_rcnn/lib/python3.8/site-packages/torchvision/models/detection/rpn.py", line 330, in forward
    features = list(features.values())
AttributeError: 'InceptionOutputs' object has no attribute 'values'

I am using the following environment:

• Ubuntu 18.04.4 LTS
• CUDA Version: 10.2
• Python: 3.8.6
• Pytorch: 1.7.0

It will be great if someone can help me in resolving this issue.
Thanks

Start with the linked tutorial and compare the MobileNetV2 and InceptionV3 backbone setup, then trace the failure from vision/engine.py into torchvision/models/detection/rpn.py. Determine why InceptionOutputs is passed where the RPN expects features, and verify that the modified Faster R-CNN model can complete training without this AttributeError.