我拥有 Kubuntu 15.10 并kubuntu-ppa/backports已kubuntu-ppa/ppa启用。昨天发布了一些更新（我猜是 5.5.3）。现在我无法登录：
.xsession-errors
This application failed to start because it could not find or load the Qt platform plugin "xcb".
Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.
Reinstalling the application may fix this problem.
startkde: Starting up...
dbus-update-activation-environment: warning: error sending to systemd: org.freedesktop.DBus.Error.Spawn.ChildExited: Process org.freedesktop.systemd1 exited with status 1
kdeinit5: preparing to launch 'libkdeinit5_klauncher'
kdeinit5: Launched KLauncher, pid = 2221, result = 0
This application failed to start because it could not find or load the Qt platform plugin "xcb".
Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.
Reinstalling the application may fix this problem.
kdeinit5: Communication error with launcher. Exiting!
kdeinit5_wrapper: Warning: connect(/run/user/1000/kdeinit5__0) failed: : Connection refused
This application failed to start because it could not find or load the Qt platform plugin "xcb".
Available platform plugins are: linuxfb, minimal, minimalegl, offscreen.
Reinstalling the application may fix this problem.
Aborted
/usr/bin/startkde: 1: /usr/bin/startkde: kreadconfig5: not found
startkde: Shutting down...
kdeinit5_wrapper: Warning: connect(/run/user/1000/kdeinit5__0) failed: : Connection refused
Error: Can not contact kdeinit5!
startkde: Done.
我已经手动安装了libkf5config-bin，kreadconfig5现在可以使用，但是消息“此应用程序无法启动，因为它找不到或加载 Qt 平台插件“xcb”。”仍然存在，不允许我登录。
我应该等待下一次更新吗？或者我现在可以修复此问题吗？
答案1
安装libqt5xcbqpa5帮助了我：
sudo apt install libqt5xcbqpa5
咆哮：在我看来，这有点故意——J. Riddell 现在一定很高兴。