This contains information about version of fcitx and some other Fcitx state. One of the common cause of "cannot use fcitx" is that, fcitx is not running at all. It could be that fcitx is autostarted properly when your desktop does not support XDG-autostart or not using some other mechanisms. You can check Setup Fcitx 5 for more details on this topic, but it could also be that fcitx crashed. As for crashes, we will come back to this topic later.