Qt Platform Plugin [better] -

find /usr/lib/qt5/plugins/platforms -name "*.so" Should list libqxcb.so , libqoffscreen.so , etc.

Windows: Look in C:\Qt\<version>\<compiler>\plugins\platforms\qwindows.dll ./myapp -platform minimal # for headless test ./myapp -platform xcb # force X11 on Linux 5.5 Check library dependencies (Linux) ldd /usr/lib/qt5/plugins/platforms/libqxcb.so | grep "not found" Install missing xcb libraries. 5.6 For bundled/deployed applications Ensure your app directory contains: qt platform plugin