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This article contains various sections to help KDE users troubleshoot their systems.

Rebuilding the application database

If the KMenu lacks any application or the whole application list, the KDE application database probably needs to be rebuilt. This is also a possible fix for any KMenu related issues, like missing icons.

user $kbuildsycoca5 --noincremental

Akonadi complains about the MySQL config

Start by checking the permissions in /usr/share/config. If they're 700, update them to 755 recursively.

root #chmod -R 755 /usr/share/config

If that doesn't solve the error, open the akonadi configuration in ~/.config/akonadi/akonadiserverrc and change the default MySQL config. To use a MySQL server and not the local mysqld executable, make sure that MySQL is running.

Black screen after login

Make sure ~/.bash_profile does not have any interactive components like keychain. Check ~/.xsession-errors for the prompt for input.

Screen Tearing/Flicker when using Radeon graphics drivers

If there is severe flickering or "tearing" when using Radeon based graphics cards, it may be necessary to change the Compositor sync settings to something other than the default "Automatic":

CODE Modifying Compositor sync settings
System Settings --> Display Monitor --> Compositor --> VSync

Delayed response of KMenu, krunner etc.

Remove gles2 USE flag and rebuild affected packages, most importantly the (installed) packages from the dev-qt category, as well as kde-frameworks/plasma and kde-plasma/kwin.

Missing shutdown/reboot/suspend/hibernate buttons

Missing features like these are often symptoms of not using kde-plasma/plasma-meta. It only provides the desktop and is highly configurable with USE flags. Use it.

Make sure that kde-plasma/powerdevil and sys-power/upower are installed. Also check that the user is in the users group.

KDE Plasma High CPU usage

If you are noticing relatively high CPU usage (normally the dbus-daemon or kwin_x11 processes) when running KDE plasma make sure to check your syslog for errors that look like the following. Normally just tailing the log will enable you to see this right away since the error is thrown at such a high rate.

FILE /var/log/syslog
Oct 17 00:30:26 localhost obexd[32399]: obex_server_init failed 
Oct 17 00:30:26 localhost obexd[32401]: OBEX daemon 5.39 
Oct 17 00:30:26 localhost obexd[32401]: obex_server_init failed 
Oct 17 00:30:26 localhost obexd[32403]: OBEX daemon 5.39

This occurs due to being unable to connect to the bluetooth service you can ensure this is started by running /etc/init.d/bluetooth start. To ensure this doesn't happen on any other start run the following.

root #rc-update add bluetooth

Alternatively you can turn off bluetooth setting via the GUI.

CODE Modifying Bluetooth settings
System Settings --> Bluetooth --> Advanced Settings --> Enable Bluetooth integration

Compilation failure

dev-qt/qtwebkit is one of the few packages known to consistently fail when the j value on MAKEOPTS is set too high. If you see mysterious build failure, try lowering your j value. The safe value would be the number of processor times thread (not that plus one).

Similar case has been found when compiling with j option while KDE is running (observed with dev-qt/qtwebkit and dev-qt/qtwebengine). The build failure would be accompanied with desktop program lagging (or crashing). If this happen, you might want to consider compiling under TTY.

In other case when you see out-of-memory failure, you may want to get rid of pipe on CFLAGS.

Plasma Browser Integration not working in Firefox

For the Plasma Browser Integration to work, not only must kde-plasma/plasma-browser-integration and the browser extension be installed, but also the browser history has to be enabled.

Consolekit specific issues

There are known issues when using consolekit and below workarounds are discouraged. Switch to elogind instead.

Unable to mount devices using KDE Plasma Device Notifier

If the error message "You are not authorized to mount this device." is being displayed when trying to mount devices by clicking on them in the KDE Plasma Device Notifier (USB-stick-like icon in the system tray), add the following file to the configuration:

FILE /etc/polkit-1/rules.d/10-udisks.rules
polkit.addRule(function(action, subject) {
	if (action.id.indexOf("org.freedesktop.udisks2.filesystem-mount") == 0 && subject.isInGroup("plugdev")) {
		return polkit.Result.YES;

This will allow all users who are members of the plugdev group to mount devices using the Device Notifier.

Use the following command to add users to this group:

root #gpasswd -a <username> plugdev
A reboot may be required for the changes to take effect.

Missing shutdown/reboot/suspend/hibernate buttons (with consolekit)

Ensure dbus is added to the default runlevel so that it is started before logging in with sddm:

root #rc-update add dbus default

If x11-misc/sddm is used, run the following command and make sure it matches the output including nox11:

user $grep pam_ck_connector /etc/pam.d/system-login
session         optional        pam_ck_connector.so nox11

Another option is to create the following polkit rule for suspend (as per this comment from the KDE bugzilla):

FILE /etc/polkit-1/rules.d/10-suspend.rules
polkit.addRule(function(action, subject) {
    if (action.id == "org.freedesktop.upower.suspend") {
        return polkit.Result.YES;

If all else fails, try x11-misc/lightdm instead.

See also