title: QT "Could not find the Qt platform plugin "xcb" "
body: <p>I installed QT-everywhere 5.15 open-source for academic reasons, but I have failed to run a program.</p>
  <p>Firstly, I compiled the necessary source files with <code>make</code> and installed the QT Creator, then I selected qmake for running programs inside it. When I tried to run an example program, I encounter this error:</p>
  <pre><code>qt.qpa.plugin: Could not find the Qt platform plugin &quot;xcb&quot; in &quot;/usr/lib/x86-64-linux-gnu&quot;
  This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
  Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc.
  The program has unexpectedly finished.
  The process was ended forcefully.
  </code></pre>
  <p>Then I looked into <code>/usr/lib/x86-64-linux-gnu</code> for finding the xcb plugin and set <code>LD_LIBRARY_PATH=/usr/lib/x86-64-linux-gnu</code>, but again the same error appeared.</p>
  <p>What should I do to solve this problem?</p>