title: I cannot use opencv2 and received ImportError: libgl.so.1 cannot open shared object file no such file or directory
body: <p>**env:**ubuntu16.04 anaconda3 python3.7.8 cuda10.0 gcc5.5</p>
  <p><strong>command:</strong></p>
  <pre><code>conda activate myenv
  python
  import cv2
  </code></pre>
  <p><strong>error:</strong>
  Traceback (most recent call last):
  File &quot;&quot;, line 1, in 
  File &quot;/home/.conda/envs/myenv/lib/python3.7/site-packages/cv2/__init__.py&quot;, line 5, in 
  from .cv2 import *
  ImportError: libGL.so.1: cannot open shared object file: No such file or directory</p>
  <p><strong>I tried:</strong></p>
  <pre><code>RUN apt install libgl1-mesa-glx -y
      RUN apt-get install 'ffmpeg'\
          'libsm6'\
          'libxext6'  -y
  </code></pre>
  <p><strong>but this is already installed and the latest version(libgl1-mesa-glx18.0.5-0ubuntu0~16.04.1).
  then i tried:</strong></p>
  <pre><code>sudo apt-get install --reinstall libgl1-mesa-glx
  </code></pre>
  <p><strong>it doesn't work.
  finally,I tried to remove the package:</strong></p>
  <pre><code>sudo apt-get --purge remove libgl1-mesa-glx
  </code></pre>
  <p><strong>another error occurred：</strong></p>
  <pre><code>Reading package list... Done
  Analyzing the dependency tree of the package
  Reading status information... Done
  Some packages cannot be installed. If you are using an unstable distribution, this may be
  Because the system cannot reach the state you requested. There may be some software you need in this version
  The packages have not been created yet or they have been moved out of the Incoming directory.
  The following information may be helpful in solving the problem:
  
  The following packages have unmet dependencies:
   libqt5multimedia5-plugins: Dependency: libqgsttools-p1 (&gt;= 5.5.1) but it will not be installed
  E: Error, pkgProblemResolver::Resolve failed. This may be due to a software package being required to maintain the status quo.
  </code></pre>
  <p><strong>Any help would be really helpful.Thanks in advance.</strong></p>
  <p><strong>conda list:</strong></p>
  <pre><code># packages in environment at /home/lwy/.conda/envs/mmdet1:
  #
  # Name                    Version                   Build  Channel
  _libgcc_mutex             0.1                 conda_forge    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  _openmp_mutex             4.5                       1_gnu    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  addict                    2.3.0                     &lt;pip&gt;
  albumentations            0.5.1                     &lt;pip&gt;
  appdirs                   1.4.4                     &lt;pip&gt;
  asynctest                 0.13.0                    &lt;pip&gt;
  attrs                     20.2.0                    &lt;pip&gt;
  ca-certificates           2020.6.20            hecda079_0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  certifi                   2020.6.20        py37he5f6b98_2    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  chardet                   3.0.4                     &lt;pip&gt;
  cityscapesScripts         2.1.7                     &lt;pip&gt;
  codecov                   2.1.10                    &lt;pip&gt;
  coloredlogs               14.0                      &lt;pip&gt;
  coverage                  5.3                       &lt;pip&gt;
  cycler                    0.10.0                    &lt;pip&gt;
  Cython                    0.29.21                   &lt;pip&gt;
  decorator                 4.4.2                     &lt;pip&gt;
  flake8                    3.8.4                     &lt;pip&gt;
  future                    0.18.2                    &lt;pip&gt;
  humanfriendly             8.2                       &lt;pip&gt;
  idna                      2.10                      &lt;pip&gt;
  imagecorruptions          1.1.0                     &lt;pip&gt;
  imageio                   2.9.0                     &lt;pip&gt;
  imgaug                    0.4.0                     &lt;pip&gt;
  importlib-metadata        2.0.0                     &lt;pip&gt;
  iniconfig                 1.1.1                     &lt;pip&gt;
  isort                     5.6.4                     &lt;pip&gt;
  kiwisolver                1.3.1                     &lt;pip&gt;
  kwarray                   0.5.10                    &lt;pip&gt;
  ld_impl_linux-64          2.35                 h769bd43_9    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  libffi                    3.2.1                         1    https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free
  libgcc-ng                 9.3.0               h5dbcf3e_17    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  libgomp                   9.3.0               h5dbcf3e_17    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  libstdcxx-ng              9.3.0               h2ae2ef3_17    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  matplotlib                3.3.2                     &lt;pip&gt;
  mccabe                    0.6.1                     &lt;pip&gt;
  mmcv                      1.1.6                     &lt;pip&gt;
  mmdet                     1.2.0+unknown             &lt;pip&gt;
  ncurses                   6.2                  he1b5a44_2    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  networkx                  2.5                       &lt;pip&gt;
  numpy                     1.19.4                    &lt;pip&gt;
  opencv-python             4.4.0.46                  &lt;pip&gt;
  openssl                   1.1.1h               h516909a_0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  ordered-set               4.0.2                     &lt;pip&gt;
  packaging                 20.4                      &lt;pip&gt;
  Pillow                    6.2.2                     &lt;pip&gt;
  pip                       20.2.4                     py_0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  pluggy                    0.13.1                    &lt;pip&gt;
  py                        1.9.0                     &lt;pip&gt;
  pycocotools               2.0                       &lt;pip&gt;
  pycodestyle               2.6.0                     &lt;pip&gt;
  pyflakes                  2.2.0                     &lt;pip&gt;
  pyparsing                 2.4.7                     &lt;pip&gt;
  pyquaternion              0.9.9                     &lt;pip&gt;
  pytest                    6.1.2                     &lt;pip&gt;
  pytest-cov                2.10.1                    &lt;pip&gt;
  pytest-runner             5.2                       &lt;pip&gt;
  python                    3.7.8           h6f2ec95_1_cpython    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  python-dateutil           2.8.1                     &lt;pip&gt;
  python_abi                3.7                     1_cp37m    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  PyWavelets                1.1.1                     &lt;pip&gt;
  PyYAML                    5.3.1                     &lt;pip&gt;
  readline                  8.0                  he28a2e2_2    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  requests                  2.24.0                    &lt;pip&gt;
  scikit-image              0.17.2                    &lt;pip&gt;
  scipy                     1.5.3                     &lt;pip&gt;
  setuptools                49.6.0           py37he5f6b98_2    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  Shapely                   1.7.1                     &lt;pip&gt;
  six                       1.15.0                    &lt;pip&gt;
  sqlite                    3.33.0               h4cf870e_1    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  tifffile                  2020.10.1                 &lt;pip&gt;
  tk                        8.6.10               hed695b0_1    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  toml                      0.10.2                    &lt;pip&gt;
  torch                     1.5.0+cu92                &lt;pip&gt;
  torchvision               0.6.0+cu92                &lt;pip&gt;
  tqdm                      4.51.0                    &lt;pip&gt;
  typing                    3.7.4.3                   &lt;pip&gt;
  ubelt                     0.9.3                     &lt;pip&gt;
  urllib3                   1.25.11                   &lt;pip&gt;
  wheel                     0.35.1             pyh9f0ad1d_0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  xdoctest                  0.15.0                    &lt;pip&gt;
  xz                        5.2.5                h516909a_1    https://mirrors.tuna.tsinghua.edu.cn/anaconda/cloud/conda-forge
  yapf                      0.30.0                    &lt;pip&gt;
  zipp                      3.4.0                     &lt;pip&gt;
  zlib                      1.2.11                        0    https://mirrors.tuna.tsinghua.edu.cn/anaconda/pkgs/free
  </code></pre>