_C.cpython-38-x86_64-linux-gnu.so: undefined symbol: _ZN6caffe28TypeMeta21_typeMetaDataInstanceIdEEPKNS_6detail12TypeMetaDataEv
What is the reason for this error and how can I fix it? I am running the code from this repo: https://github.com/facebookresearch/frankmocap
(frank) mona@goku:~/research/code/frankmocap$ python -m demo.demo_frankmocap --input_path ./sample_data/han_short.mp4 --out_dir ./mocap_output
Traceback (most recent call last):
  File &quot;/usr/lib/python3.8/runpy.py&quot;, line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File &quot;/usr/lib/python3.8/runpy.py&quot;, line 87, in _run_code
    exec(code, run_globals)
  File &quot;/home/mona/research/code/frankmocap/demo/demo_frankmocap.py&quot;, line 25, in &lt;module&gt;
    from handmocap.hand_bbox_detector import HandBboxDetector
  File &quot;/home/mona/research/code/frankmocap/handmocap/hand_bbox_detector.py&quot;, line 33, in &lt;module&gt;
    from detectors.hand_object_detector.lib.model.roi_layers import nms # might raise segmentation fault at the end of program
  File &quot;/home/mona/research/code/frankmocap/detectors/hand_object_detector/lib/model/roi_layers/__init__.py&quot;, line 3, in &lt;module&gt;
    from .nms import nms
  File &quot;/home/mona/research/code/frankmocap/detectors/hand_object_detector/lib/model/roi_layers/nms.py&quot;, line 3, in &lt;module&gt;
    from model import _C
ImportError: /home/mona/research/code/frankmocap/detectors/hand_object_detector/lib/model/_C.cpython-38-x86_64-linux-gnu.so: undefined symbol: _ZN6caffe28TypeMeta21_typeMetaDataInstanceIdEEPKNS_6detail12TypeMetaDataEv

I have:
$ lsb_release -a
LSB Version:    core-11.1.0ubuntu2-noarch:security-11.1.0ubuntu2-noarch
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.2 LTS
Release:    20.04
Codename:   focal

and
$ python
Python 3.8.5 (default, Jan 27 2021, 15:41:15) 
[GCC 9.3.0] on linux
Type &quot;help&quot;, &quot;copyright&quot;, &quot;credits&quot; or &quot;license&quot; for more information.
&gt;&gt;&gt; import torch
&gt;&gt;&gt; torch.__version__
'1.8.1+cu111'
&gt;&gt;&gt; import detectron2
&gt;&gt;&gt; detectron2.__version__
'0.4'
&gt;&gt;&gt; from detectron2 import _C

and:
$ python -m detectron2.utils.collect_env
/home/mona/venv/frank/lib/python3.8/site-packages/torch/cuda/__init__.py:52: UserWarning: CUDA initialization: Unexpected error from cudaGetDeviceCount(). Did you run some cuda functions before calling NumCudaDevices() that might have already set an error? Error 804: forward compatibility was attempted on non supported HW (Triggered internally at  /pytorch/c10/cuda/CUDAFunctions.cpp:109.)
  return torch._C._cuda_getDeviceCount() &gt; 0
No CUDA runtime is found, using CUDA_HOME='/usr'
---------------------  --------------------------------------------------------------------------
sys.platform           linux
Python                 3.8.5 (default, Jan 27 2021, 15:41:15) [GCC 9.3.0]
numpy                  1.19.5
detectron2             0.4 @/home/mona/venv/frank/lib/python3.8/site-packages/detectron2
Compiler               GCC 7.3
CUDA compiler          CUDA 11.1
DETECTRON2_ENV_MODULE  &lt;not set&gt;
PyTorch                1.8.1+cu111 @/home/mona/venv/frank/lib/python3.8/site-packages/torch
PyTorch debug build    False
GPU available          False
Pillow                 8.1.0
torchvision            0.9.1+cu111 @/home/mona/venv/frank/lib/python3.8/site-packages/torchvision
fvcore                 0.1.3.post20210311
cv2                    4.5.1
---------------------  --------------------------------------------------------------------------
PyTorch built with:
  - GCC 7.3
  - C++ Version: 201402
  - Intel(R) Math Kernel Library Version 2020.0.0 Product Build 20191122 for Intel(R) 64 architecture applications
  - Intel(R) MKL-DNN v1.7.0 (Git Hash 7aed236906b1f7a05c0917e5257a1af05e9ff683)
  - OpenMP 201511 (a.k.a. OpenMP 4.5)
  - NNPACK is enabled
  - CPU capability usage: AVX2
  - Build settings: BLAS_INFO=mkl, BUILD_TYPE=Release, CUDA_VERSION=11.1, CUDNN_VERSION=8.0.5, CXX_COMPILER=/opt/rh/devtoolset-7/root/usr/bin/c++, CXX_FLAGS= -Wno-deprecated -fvisibility-inlines-hidden -DUSE_PTHREADPOOL -fopenmp -DNDEBUG -DUSE_KINETO -DUSE_FBGEMM -DUSE_QNNPACK -DUSE_PYTORCH_QNNPACK -DUSE_XNNPACK -O2 -fPIC -Wno-narrowing -Wall -Wextra -Werror=return-type -Wno-missing-field-initializers -Wno-type-limits -Wno-array-bounds -Wno-unknown-pragmas -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable -Wno-unused-function -Wno-unused-result -Wno-unused-local-typedefs -Wno-strict-overflow -Wno-strict-aliasing -Wno-error=deprecated-declarations -Wno-stringop-overflow -Wno-psabi -Wno-error=pedantic -Wno-error=redundant-decls -Wno-error=old-style-cast -fdiagnostics-color=always -faligned-new -Wno-unused-but-set-variable -Wno-maybe-uninitialized -fno-math-errno -fno-trapping-math -Werror=format -Wno-stringop-overflow, LAPACK_INFO=mkl, PERF_WITH_AVX=1, PERF_WITH_AVX2=1, PERF_WITH_AVX512=1, TORCH_VERSION=1.8.1, USE_CUDA=ON, USE_CUDNN=ON, USE_EXCEPTION_PTR=1, USE_GFLAGS=OFF, USE_GLOG=OFF, USE_MKL=ON, USE_MKLDNN=ON, USE_MPI=OFF, USE_NCCL=ON, USE_NNPACK=ON, USE_OPENMP=ON, 


I tried the solutions mentioned here, but that didn't fully solve the problem. However, when I tried solving a different error using this solution, it also solved this error for me. Use the following command:
pip install torch==1.8.0+cu111 torchvision==0.9.0+cu111 torchaudio==0.8.0 -f https://download.pytorch.org/whl/torch_stable.html

