First stop: if you use conda, please read our page on QT incompatibilities with conda.
If you don’t use conda, but you see error messages similar to these every time you import the guietta module:
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found. 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, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl, xcb. Aborted (core dumped)
This means that some QT plugins are missing, and/or not installed correctly. Ubuntu 16.04 for example is missing the libxcb-xinerama0 in its default installation.
Turn on the plugin debug like this:
Run again the Guietta program, and you will get a lot more output with hopefully an error message, which in my case was:
Cannot load library /usr/local/lib/python3.5/dist-packages/PySide2/Qt/plugins/platforms/libqxcb.so: (libxcb-xinerama.so.0: cannot open shared object file: No such file or directory)
Therefore I installed libxcb-xinerama0:
sudo apt install libxcb-xinerama0
This problem and successful resolution was also reported for Ubuntu 20.04