title: lightdm_greeter_ensure_shared_data_dir_sync: assertion 'priv->connected' failed
body: <p>I am trying to use the web-greeter in LightDM in Ubuntu 20.04.3, but with every themes comes this error message.</p>
  <p>I installed the web-greeter from <a href="https://github.com/JezerM/web-greeter" rel="nofollow noreferrer">https://github.com/JezerM/web-greeter</a></p>
  <pre><code>/usr/share/web-greeter/themes$ web-greeter 
  2021-12-27 11:51:57 [ DEBUG ] screensaver - screensaver.py:30 : set_screensaver | Screensaver timeout set
  2021-12-27 11:51:57 [ DEBUG ] browser - browser.py:207 : init | Initializing Browser Window
  
  DevTools listening on ws://127.0.0.1:12345/devtools/browser/7eb554aa-8640-465c-b211-6f0b0e89f039
  NotImplementedError: QLayout.itemAt() is abstract and must be overridden
  2021-12-27 11:51:57 [ DEBUG ] browser - browser.py:280 : _initialize_devtools | DevTools initialized
  2021-12-27 11:51:57 [ DEBUG ] browser - browser.py:251 : init | Browser Window created
  2021-12-27 11:51:57 [ DEBUG ] browser - browser.py:156 : show | Window is ready
  2021-12-27 11:51:57 [ ERROR ] Greeter.py 152 : __init__ | lightdm_greeter_error: Unable to determine socket to daemon (1)
  Remote debugging server started successfully. Try pointing a Chromium-based browser to http://127.0.0.1:12345
  [4604:4625:1227/115158.088865:ERROR:render_process_host_impl.cc(4562)] Terminating render process for bad Mojo message: Received bad user message: ACDH_SELECT_CACH
  [4604:4625:1227/115158.089032:ERROR:bad_message.cc(25)] Terminating renderer for bad IPC message, reason 123
  
  ** (python3:4604): CRITICAL **: 11:51:59.502: lightdm_greeter_ensure_shared_data_dir_sync: assertion 'priv-&gt;connected' failed
  2021-12-27 11:51:59 [ DEBUG ] Greeter.py 162 : __init__ | LightDM API connected
  2021-12-27 11:51:59 [ DEBUG ] browser - browser.py:342 : load_theme | Theme loaded
  2021-12-27 11:51:59 [ DEBUG ] browser - browser.py:159 : run | Web Greeter started
  2021-12-27 11:52:08 [ DEBUG ] screensaver - screensaver.py:40 : reset_screensaver | Screensaver reset
  </code></pre>
  <p>How can I fix the error lightdm_greeter_ensure_shared_data_dir_sync: assertion 'priv-&gt;connected' failed ?</p>