title: PySide2 Cannot Find Qt_5.15
body: <p>This Friday my PySide2 installation stopped working inside an Ubuntu 18.04 container (based on nvidia/opengl:1.0-glvnd-runtime-ubuntu18.04). I now get the following error:</p>
  
  <pre><code>python3 -c "from PySide2 import QtWidgets"
  Traceback (most recent call last):
    File "&lt;string&gt;", line 1, in &lt;module&gt;
  ImportError: /usr/lib/x86_64-linux-gnu/libQt5Core.so.5: version `Qt_5.15' not found (required by /usr/local/lib/python3.6/dist-packages/PySide2/libpyside2.abi3.so.5.15)
  </code></pre>
  
  <p>I have tried to manually compile Qt via</p>
  
  <pre><code>RUN apt-get update &amp;&amp; \
      apt-get -y install -y \
      clang \
      libfontconfig1-dev \
      libfreetype6-dev \
      libx11-dev \
      libxext-dev \
      libxfixes-dev \
      libxi-dev \
      libxrender-dev \
      libxcb1-dev \
      libx11-xcb-dev \
      libxcb-glx0-dev \
      libxkbcommon-x11-dev \
      libxcb-keysyms1-dev \
      libxcb-image0-dev \
      libxcb-shm0-dev \
      libxcb-icccm4-dev \
      libxcb-sync0-dev \
      libxcb-xfixes0-dev \
      libxcb-shape0-dev \
      libxcb-randr0-dev \
      libxcb-render-util0-dev &amp;&amp; \
      rm -rf /var/lib/apt/lists/*
  
  RUN cd /tmp &amp;&amp; wget http://download.qt.io/official_releases/qt/5.15/5.15.0/single/qt-everywhere-src-5.15.0.tar.xz &amp;&amp; \
      tar -xf qt-everywhere-src-5.15.0.tar.xz &amp;&amp; tar -xf qt-everywhere-src-5.15.0.tar.xz &amp;&amp; \
      rm qt-everywhere-src-5.15.0.tar.xz &amp;&amp; cd qt-everywhere-src-5.15.0 &amp;&amp; export QT5PREFIX=/opt/qt5 &amp;&amp; \
      ./configure -prefix $QT5PREFIX \
              -sysconfdir /etc/xdg \
              -confirm-license \
              -opensource \
              -system-harfbuzz \
              -nomake examples \
              -no-rpath \
              -skip qtwebengine &amp;&amp; \
      make &amp;&amp; make install
  </code></pre>
  
  <p>(and added it to PATH) but that did not help (same error).</p>
  
  <p>I tried with the default packages as well, i.e. <code>apt install qt5-default python3-pyside python3-pip</code>, but despite installing PySide the PySide2 module is not found, so I installed it via pip as well, i.e. <code>python3 -m pip install -U pip &amp;&amp; python3 -m pip install PySide2</code>. But even then I hit the same issue again. At least here I understand it, because I installed Qt 5.9.5 by using the version in the repository.</p>
  
  <p>Could someone help me with getting the import to run so I can again run PySide2 bindings like it worked mid last week? Thank you in advance.</p>
  
  <p><strong>Appendix</strong>
  I have also tried creating a <code>/usr/lib/x86_64-linux-gnu/qt-default/qtchooser/default.conf</code> file with the content</p>
  
  <pre><code>/opt/qt5/bin
  /opt/qt5/lib
  </code></pre>
  
  <p>to point to my manually compiled Qt, but to no avail.</p>
  
  <p>UPDATE: I think this has to do with me compiling OMPL before compiling Qt which installs its own Qt version. So PySide2 then picks up the wrong version. However, I have been unable to point it to the right Qt version. Could someone recap which variables I need to set for this beyond what I have already mentioned? Thank you in advance.</p>