KDE/Troubleshooting

This article contains various sections to help users of KDE software 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.

Akonadi complains about the MySQL config
Start by checking the permissions in. If they're 700, update them to 755 recursively.

If that doesn't solve the error, open the akonadi configuration in 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 does not have any interactive components like keychain. Check 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":

Delayed response of KMenu, krunner etc.
Remove  USE flag and rebuild affected packages, most importantly the (installed) packages from the   category, as well as  and.

Missing shutdown/reboot/suspend/hibernate buttons
Make sure that and  are installed. Also check that the user is in the 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.

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

Alternatively you can turn off bluetooth setting via the GUI.

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

Similar case has been found when compiling with option while KDE Plasma is running (observed with  and ). 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 on CFLAGS.

Plasma Browser Integration not working in Firefox
For the Plasma Browser Integration to work, not only must and the browser extension be installed, but also the browser history has to be enabled.

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:

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

Use the following command to add users to this group:

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:

If is used, run the following command and make sure it matches the output including  :

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

If all else fails, try instead.