Hi @fjoseph , I hit the same problem with ubuntu16.04 and cuda10.2. I found a possible solution that we can install tensorrt and its dependencies one by one manually. The following commands work well on my machine and hope they are helpful to you.
dpkg -i nv-tensorrt-repo-ubuntu1604-cuda10.2-trt8.0.1.6-ga-20210626_1-1_amd64.deb
cd /var/nv-tensorrt-repo-ubuntu1604-cuda10.2-trt8.0.1.6-ga-20210626
dpkg -i libcudnn8_8.2.1.32-1+cuda10.2_amd64.deb
dpkg -i libcudnn8-dev_8.2.1.32-1+cuda10.2_amd64.deb
dpkg -i libnvinfer8_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvinfer-dev_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvinfer-plugin8_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvinfer-plugin-dev_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvonnxparsers8_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvonnxparsers-dev_8.0.1-1+cuda10.2_amd64.deb
dpkg -i onnx-graphsurgeon_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvparsers8_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvparsers-dev_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvinfer-bin_8.0.1-1+cuda10.2_amd64.deb
dpkg -i python3-libnvinfer_8.0.1-1+cuda10.2_amd64.deb
dpkg -i python3-libnvinfer-dev_8.0.1-1+cuda10.2_amd64.deb
dpkg -i libnvinfer-samples_8.0.1-1+cuda10.2_all.deb
dpkg -i libnvinfer-doc_8.0.1-1+cuda10.2_all.deb
dpkg -i tensorrt_8.0.1.6-1+cuda10.2_amd64.deb