KDE (한국어)
KDE는 데스크탑 환경인 Plasma를 포함하는 소프트웨어 프로젝트이다. 또한, KDE는 라이브러리의 모음인 KDE 프레임워크와 그 외의 어플리케이션인 KDE 어플리케이션을 포함한다. KDE에 관해서는 현재 운영되고 있는 유저베이스 위키가 존재한다. KDE에 관한 더 자세한 정보는 이 곳에서 찾을 수 있다.
설치
Plasma
Plasma를 설치하기 전에, 시스템에 작동하는 Xorg가 존재하는 지 확인하여야 한다.
메타 패키지인 plasma-meta 혹은 그룹 plasma을 설치하면 된다. 메타 패키지와 그룹의 차이점에 대해서는 패키지 그룹 문서를 참고 할 것. 더 적은 구성요소로 Plasma를 설치하고 싶은 경우에는 plasma-desktop 패키지를 설치하는 것으로 충분하다.
Wayland 지원을 활성화하기 위해서는, plasma-wayland-session 패키지 또한 설치하여야 한다.
KDE 어플리케이션
KDE 어플리케이션에 해당하는 어플리케이션을 전부 설치하기를 원한다면, kde-applications 그룹 혹은 kde-applications-meta 메타 패키지를 설치하면 된다. 이 패키지를 설치할 경우, 어플리케이션만이 설치되고, Plasma는 설치되지 않는다.
불안정한 버전
Plasma 시작하기
Plasma는 디스플레이 매니저 혹은 콘솔을 이용하여 시작할 수 있다.
디스플레이 매니저를 사용하는 경우
- Plasma를 선택하여 Xorg의 새로운 세션을 시작할 수 있다.
- plasma-wayland-session를 설치하였다면, Plasma (Wayland)를 설치하여 새로운 세션을 Wayland에서 시작하는 것이 가능하다.
콘솔을 이용하는 경우
-
xinit을 이용하는 경우,
export DESKTOP_SESSION=plasma와exec startplasma-x11를.xinitrc파일에 추가하여야 한다. Xorg가 로그인 시에 시작되기를 원한다면 Start X at login를 참고. - Plasma의 Wayland 세션을 콘솔에서 시작하기 원하는 경우,
XDG_SESSION_TYPE=wayland dbus-run-session startplasma-wayland를 실행할 것. 참고: [1]
Configuration
Most settings for KDE applications are stored in ~/.config/. However, configuring KDE is primarily done through the System Settings application. It can be started from a terminal by executing systemsettings.
Personalization
Plasma desktop
테마
Plasma themes define the look of panels and Plasma widgets. For easy system-wide installation, some themes are available in both the official repositories and the AUR.
Plasma themes can also be installed through System Settings > Global Theme > Get New Global Themes....
The KDE Store offers more Plasma customizations, like SDDM themes and splash-screens.
GTK application appearance
The recommended theme for a pleasant appearance in GTK applications is breeze-gtk, a GTK theme designed to mimic the appearance of Plasma's Breeze theme.
Install kde-gtk-config (part of the plasma group) and select Breeze or Breeze-Dark as the GTK2/GTK3 theme in System Settings > Application Style > Configure GNOME/GTK Application Style....
In some themes, tooltips in GTK applications have white text on white backgrounds making it difficult to read. To change the colors in GTK2 applications, find the section for tooltips in the .gtkrc-2.0 file and change it. For GTK3 application two files need to be changed, gtk.css and settings.ini.
Some GTK2 programs like vuescan-binAUR still look hardly usable due to invisible checkboxes with the Breeze or Adwaita skin in a Plasma session. To workaround this, install and select e.g. the Numix-Frost-Light skin of the numix-frost-themesAUR under System Settings > Application Style > Configure GNOME/GTK Application Style... > GTK2 theme:. Numix-Frost-Light looks similar to Breeze.
Faces
Plasma and SDDM will both use a PNG file found at ~/.face.icon as a user's avatar. To configure with a graphical interface, you can use System Settings > Accounts Details > User Manager. The default icon can be found in /usr/share/sddm/faces/.
Plasmoid 위젯
Plasmoids are little scripted (plasmoid scripts) or coded (plasmoid binaries) KDE applications designed to enhance the functionality of your desktop.
The easiest way to install plasmoid scripts is by right-clicking onto a panel or the desktop and choosing Add Widgets > Get New Widgets... > Download New Plasma Widgets. This will present a nice frontend for https://store.kde.org/ that allows you to install, uninstall, or update third-party plasmoid scripts with literally just one click.
Many Plasmoid binaries are available from the AUR.
Sound applet in the system tray
Install plasma-pa or kmix (start Kmix from the Application Launcher). plasma-pa is now installed by default with plasma, no further configuration needed.
VolumePercentageStep=1 in the [Global] section of ~/.config/kmixrc.Disable panel shadow
As the Plasma panel is on top of other windows, its shadow is drawn over them. [2] To disable this behaviour without impacting other shadows, install xorg-xprop and run:
$ xprop -remove _KDE_NET_WM_SHADOW
then select the panel with the plus-sized cursor. [3] For automation, install xorg-xwininfo and create the following script:
/usr/local/bin/kde-no-shadow
#!/bin/bash
for WID in $(xwininfo -root -tree | sed '/"Plasma": ("plasmashell" "plasmashell")/!d; s/^ *\([^ ]*\) .*/\1/g'); do
xprop -id $WID -remove _KDE_NET_WM_SHADOW
done
Set execution permissions for the script:
# chmod 755 /usr/local/bin/kde-no-shadow
The script can be run on login with Add Script in Autostart:
$ kcmshell5 autostart
창 장식
창 장식은 System Settings > 모양새 > 창 장식에서 변경할 수 있다.
설정에서 자신이 원하는 테마를 쉽게 설치할 수 있으며, 일부 테마는 AUR에서도 받을 수 있다.
Icon themes
Icon themes can be installed and changed on System Settings > Icons.
breeze to the Inherits= array in /usr/share/icon/theme-name/index.theme, for example: Inherits=breeze,hicolor. You need to reapply this patch after every update to the icon theme, consider using Pacman hooks to automate the process.Space efficiency
The Plasma Netbook shell has been dropped from Plasma 5, see the following KDE forum post. However, you can achieve something similar by editing the file ~/.config/kwinrc adding BorderlessMaximizedWindows=true in the [Windows] section.
Thumbnail generation
To allow thumbnail generation for media or document files on the desktop and in Dolphin, install kdegraphics-thumbnailers and ffmpegthumbs.
Then enable the thumbnail categories for the desktop via right click on the desktop background > Configure Desktop > Icons > Configure Preview Plugins....
In Dolphin, navigate to Control > Configure Dolphin... > General > Previews.
Night Color
Plasma provides a Redshift-like feature (working on both Xorg and Wayland) called Night Color. It makes the colors on the screen warmer to reduce eye strain at the time of your choosing. It can be enabled in System Settings > Display and Monitor > Night Color.
Printing
You can also configure printers in System Settings > Printers. To use this method, you must first install the following packages print-manager, cups, system-config-printer. See CUPS#Configuration.
Samba/Windows support
If you want to have access to Windows services, install Samba (package samba).
The Dolphin share functionality requires the package kdenetwork-filesharing and usershares, which the stock smb.conf does not have enabled. Instructions to add them are in Samba#Enable Usershares, after which sharing in Dolphin should work out of the box after restarting Samba.
* (asterisk) for both username and password when accessing a Windows share without authentication in Dolphin's prompt.Unlike GTK file browsers which utilize GVfs also for the launched program, opening files from Samba shares in Dolphin via KIO makes Plasma copy the whole file to the local system first with most programs (VLC is an exception). To workaround this, you can use a GTK based file browser like thunar with gvfs and gvfs-smb (and gnome-keyring for saving login credentials) to access SMB shares in a more able way.
Another possibility is to mount a Samba share via cifs-utils to make it look to Plasma like if the SMB share was just a normal local folder and thus can be accessed normally. See Samba#Manual mounting and Samba#Automatic mounting.
An GUI solution is available with samba-mounter-gitAUR, which offers basically the same functionality via an easy to use option located at System Settings > Network Drivers. However, it might break with new KDE Plasma versions.
KDE Desktop activities
KDE Desktop Activities are special workspaces where you can select specific settings for each activity that apply only when you are using said activity.
Power management
Install powerdevil for an integrated Plasma power managing service. This service offers additional power saving features, monitor brightness control (if supported) and battery reporting including peripheral devices.
An alternative package without NetworkManager and Bluez dependencies is provided by powerdevil-lightAUR.
Autostart
Plasma can autostart applications and run scripts on startup and shutdown. To autostart an application, navigate to System Settings > Startup and Shutdown > Autostart and add the program or shell script of your choice. For applications, a .desktop file will be created, for shell scripts, a symlink will be created.
- Programs can be autostarted on login only, whilst shell scripts can also be run on shutdown or even before Plasma itself starts.
- Shell scripts will only be run if they are marked executable.
- Place Desktop entries (i.e. .desktop files) in the appropriate XDG Autostart directory.
- Place or symlink shell scripts in one of the following directories:
~/.config/plasma-workspace/env/- for executing scripts at login before launching Plasma.
~/.config/autostart-scripts/- for executing scripts at login.
~/.config/plasma-workspace/shutdown/- for executing scripts when Plasma exits.
Phonon
From Wikipedia:
- Phonon is the multimedia API provided by KDE and is the standard abstraction for handling multimedia streams within KDE software and also used by several Qt applications.
- Phonon was originally created to allow KDE and Qt software to be independent of any single multimedia framework such as GStreamer or xine and to provide a stable API for a major version's lifetime.
Phonon is being widely used within KDE, for both audio (e.g., the System notifications or KDE audio apps) and video (e.g., the Dolphin video thumbnails).
Which backend should I choose?
You can choose between backends based on GStreamer and VLC – each available in versions for Qt4 applications and Qt5 applications (phonon-qt4-gstreamerAUR, phonon-qt5-gstreamer – phonon-qt4-vlcAUR, phonon-qt5-vlc).
Upstream prefers VLC but prominent Linux distributions (Kubuntu and Fedora-KDE for example) prefer GStreamer because that allows them to easily leave out patented MPEG codecs from the default installation. Both backends have a slightly different features set. The Gstreamer backend has some optional codec dependency, install them as needed:
- gst-libav — Libav codecs.
- gst-plugins-good — PulseAudio support and additional codecs.
- gst-plugins-ugly — additional codecs.
- gst-plugins-bad — additional codecs.
In the past other backends were developed as well but are no longer maintained and their AUR packages have been deleted.
- Multiple backends can be installed at once and prioritized via the phononsettings application.
- According to the KDE forums, the VLC backend lacks support for ReplayGain.
- If using the VLC backend, you may experience crashes every time Plasma wants to send you an audible warning and in quite a number of other cases as well [5]. A possible fix is to rebuild the VLC plugins cache:
# /usr/lib/vlc/vlc-cache-gen /usr/lib/vlc/plugins
Backup and restore
KDE Plasma 5 stores personalized desktop settings as configuration files in the XDG_CONFIG_HOME folder. Use the detail of configuration files to select and choose a method of backup and restore.
Applications
The KDE project provides a suite of applications that integrate with the Plasma desktop. See the kde-applications group for a full listing of the available applications. Also see Category:KDE for related KDE application pages.
Aside from the programs provided in KDE Applications, there are many other applications available that can complement the Plasma desktop. Some of these are discussed below.
System administration
Terminate Xorg server through KDE System Settings
Navigate to the submenu System Settings > Input Devices > Keyboard > Advanced (tab) > "Key Sequence to kill the X server" and ensure that the checkbox is ticked.
KCM
KCM stands for KConfig Module. KCMs can help you configure your system by providing interfaces in System Settings, or through the command line with kcmshell5.
- sddm-kcm — KDE Config Module for SDDM.
- kde-gtk-config — GTK2 and GTK3 Configurator for KDE.
- System policies — Set of configuration modules which allows administrator to change PolicyKit settings.
- wacom tablet — KDE GUI for the Wacom Linux Drivers.
- Kcmsystemd — systemd control module for KDE.
More KCMs can be found at linux-apps.com.
Desktop search
KDE implements desktop search with a software called Baloo, a file indexing and searching solution.
Web browsers
The following web browsers can integrate with Plasma:
- Konqueror — Part of the KDE project, supports two rendering engines – KHTML and the Chromium-based Qt WebEngine.
- Falkon — A Qt web browser with Plasma integration features, previously known as Qupzilla. It uses Qt WebEngine.
- Chromium — Chromium and its proprietary variant Google Chrome have limited Plasma integration. They can use KWallet and KDE Open/Save windows.
- Firefox — Firefox can be configured to better integrate with Plasma. See Firefox KDE integration for details.
PIM
KDE offers its own stack for personal information management (PIM). This includes emails, contacts, calendar, etc. To install all the PIM packages, you could use the kdepim[broken link: package not found] package group or the kde-pim-meta meta package.
Akonadi
Akonadi is a system meant to act as a local cache for PIM data, regardless of its origin, which can be then used by other applications. This includes the user's emails, contacts, calendars, events, journals, alarms, notes, and so on. Akonadi does not store any data by itself: the storage format depends on the nature of the data (for example, contacts may be stored in vCard format).
Install akonadi. For additional addons, install kdepim-addons.
# pacman -S akonadi --assume-installed mariadb
See also FS#32878.
MySQL
By default Akonadi will use /usr/bin/mysqld (MariaDB by default, see MySQL for alternative providers) to run a managed MySQL instance with the database stored in ~/.local/share/akonadi/db_data/.
System-wide MySQL instance
Akonadi supports using the system-wide MySQL for its database.[6]
~/.config/akonadi/akonadiserverrc
[%General] Driver=QMYSQL [QMYSQL] Host= Name=akonadi_username Options="UNIX_SOCKET=/run/mysqld/mysqld.sock" StartServer=false
PostgreSQL
Akonadi supports either using the existing system-wide PostgreSQL instance, i.e. postgresql.service, or running a PostgreSQL instance with user privileges and the database in ~/.local/share/akonadi/db_data/.
Per-user PostgreSQL instance
Install postgresql and postgresql-old-upgrade.
Edit Akonadi configuration file so that it has the following contents:
~/.config/akonadi/akonadiserverrc
[%General] Driver=QPSQL
- When Akonadi starts, it will create the
[QPSQL]section and set the appropriate variables in it. - The database will be stored in
~/.local/share/akonadi/db_data/.
Start Akonadi with akonadictl start, and check its status: akonadictl status.
- Starting with akonadi 19.08.0-1 the PostgreSQL database cluster in
~/.local/share/akonadi/db_data/will get automatically upgraded when a major PostgreSQL version upgrade is detected. - For previous akonadi versions major PostgreSQL version upgrades will require a manual database upgrade. Follow the update instructions on KDE UserBase Wiki. Make sure to adjust the paths to PostgreSQL binaries to those used by postgresql and postgresql-old-upgrade, see PostgreSQL#Upgrading PostgreSQL.
System-wide PostgreSQL instance
This requires an already configured and running PostgreSQL.
Create a PostgreSQL user account for your user:
[postgres]$ createuser username
Create a database for Akonadi:
[postgres]$ createdb -O username -E UTF8 --locale=C -T template0 akonadi-username
Configure Akonadi to use the system-wide PostgreSQL:
~/.config/akonadi/akonadiserverrc
[%General] Driver=QPSQL [QPSQL] Host=/run/postgresql Name=akonadi-username StartServer=false
Port=, User=, Password= in the [QPSQL] section.Start Akonadi with akonadictl start, and check its status: akonadictl status.
SQLite
To use SQLite edit Akonadi configuration file to match the configuration below:
~/.config/akonadi/akonadiserverrc
[%General] Driver=QSQLITE3
- When Akonadi starts, it will create the
[QSQLITE3]section and set the appropriate variables in it. - The database will be stored as
~/.local/share/akonadi/akonadi.db.
Disabling Akonadi
See this section in the KDE userbase.
KDE Telepathy
KDE Telepathy is a project with the goal to closely integrate Instant Messaging with the KDE desktop. It utilizes the Telepathy framework as a backend and is intended to replace Kopete.
To install all Telepathy protocols, install the telepathy group. To use the KDE Telepathy client, install the telepathy-kde-meta package that includes all the packages contained in the telepathy-kde group.
Use Telegram with KDE Telepathy
Telegram protocol is available using telepathy-haze, installing telegram-purpleAUR or telegram-purple-gitAUR and telepathy-morse-gitAUR. The username is the Telegram account telephone number (complete with the national prefix +xx, e.g. +49 for Germany).
The configuration through the GUI may be tricky: if the phone number is not accepted when configuring a new account in the KDE Telepathy client (with an error message complaining about an invalid parameter which prevents the account creation), insert it between single quotes and then remove the quotes manually from the configuration file (~/.local/share/telepathy/mission-control/accounts.cfg) after the account creation (if the quotes are not removed after, an authentication error should rise).
KDE Connect
KDE Connect provides several features to connect your Android phone with your Linux desktop:
- Share files and URLs to/from KDE from/to any app, without wires.
- Touchpad emulation: Use your phone screen as your computer's touchpad.
- Notifications sync (4.3+): Read your Android notifications from the desktop.
- Shared clipboard: copy and paste between your phone and your computer.
- Multimedia remote control: Use your phone as a remote for Linux media players.
- WiFi connection: no usb wire or bluetooth needed.
- RSA Encryption: your information is safe.
You will need to install KDE Connect both on your computer and on your Android. For PC side, install kdeconnect package. For Android side, install KDE Connect from Google Play or from F-Droid. If you want to browse your phone's filesystem, you need to install sshfs as well and configure filesystem exposes in your Android app.
It is possible to use KDE Connect even if you do not use the Plasma desktop. For desktop environments that use AppIndicators, such as Unity, install indicator-kdeconnectAUR package as well. For GNOME users, better integration can be achieved by installing gnome-shell-extension-gsconnectAUR instead of kdeconnect. To start the KDE Connect daemon manually, execute /usr/lib/kdeconnectd.
If you use a firewall, you need to open UDP and TCP ports 1714 through 1764.
Tips and tricks
Use a different window manager
The component chooser settings in Plasma does not allow changing the window manager anymore. [7]
In order to change the window manager used you need to set the KDEWM environment variable before KDE startup. The instructions are available on the KDE UserBase Wiki—Tutorials/Using Other Window Managers with Plasma.
KDE/Openbox session
The openbox package provides a session for using KDE with Openbox. To make use of this session, select KDE/Openbox from the display manager menu.
For those starting the session manually, add the following line to your xinit configuration:
~/.xinitrc
exec openbox-kde-session
Re-enabling compositing effects
When replacing Kwin with a window manager which does not provide a Compositor (such as Openbox), any desktop compositing effects e.g. transparency will be lost. In this case, install and run a separate Composite manager to provide the effects such as Xcompmgr or Compton.
Configuring monitor resolution / multiple monitors
To enable display resolution management and multiple monitors in Plasma, install kscreen. This provides additional options to System Settings > Display and Monitor.
KWin-lowlatency
KWin-lowlatency is a attempt to reduce latency and stuttering in the popular KWin compositor, and is available as kwin-lowlatencyAUR.
Configuring ICC profiles
To enable ICC profiles in Plasma, install colord-kde. This provides additional options to System Settings > Color Corrections.
ICC profiles can be imported using Add Profile.
Disable opening application launcher with Super key (Windows key)
To disable this feature you currently can run the following command:
$ kwriteconfig5 --file kwinrc --group ModifierOnlyShortcuts --key Meta ""
With Plasma Browser integration installed, KDE will show bookmarks in the application launcher.
To disable this feature you currently can run the following commands:
$ mkdir ~/.local/share/kservices5 $ sed 's/EnabledByDefault=true$/EnabledByDefault=false/' /usr/share/kservices5/plasma-runner-bookmarks.desktop > ~/.local/share/kservices5/plasma-runner-bookmarks.desktop
Troubleshooting
Fonts
Fonts in a Plasma session look poor
Try installing the ttf-dejavu and ttf-liberation packages.
After the installation, be sure to log out and back in. You should not have to modify anything in System Settings > Fonts. If you are using qt5ct, the settings in Qt5 Configuration Tool may override the font settings in System Settings.
If you have personally set up how your Fonts render, be aware that System Settings may alter their appearance. When you go System Settings > Fonts System Settings will likely alter your font configuration file (fonts.conf).
There is no way to prevent this, but, if you set the values to match your fonts.conf file, the expected font rendering will return (it will require you to restart your application or in a few cases restart your desktop). Note that Gnome's Font Preferences also does this.
Fonts are huge or seem disproportional
Try to force font DPI to 96 in System Settings > Fonts.
If that does not work, try setting the DPI directly in your Xorg configuration as documented in Xorg#Setting DPI manually.
Many problems in KDE are related to its configuration.
Plasma desktop behaves strangely
Plasma problems are usually caused by unstable Plasma widgets (colloquially called plasmoids) or Plasma themes. First, find which was the last widget or theme you had installed and disable or uninstall it.
So, if your desktop suddenly exhibits "locking up", this is likely caused by a faulty installed widget. If you cannot remember which widget you installed before the problem began (sometimes it can be an irregular problem), try to track it down by removing each widget until the problem ceases. Then you can uninstall the widget, and file a bug report on the KDE bug tracker only if it is an official widget. If it is not, it is recommended to find the entry on the KDE Store and inform the developer of that widget about the problem (detailing steps to reproduce, etc.).
If you cannot find the problem, but you do not want all the settings to be lost, navigate to ~/.config/ and run the following command:
$ for j in plasma*; do mv -- "$j" "${j%}.bak"; done
This command will rename all Plasma related configuration files to *.bak (e.g. plasmarc.bak) of your user and when you will relogin into Plasma, you will have the default settings back. To undo that action, remove the .bak file extension. If you already have *.bak files, rename, move, or delete them first. It is highly recommended that you create regular backups anyway. See Synchronization and backup programs for a list of possible solutions.
Clean cache to resolve upgrade problems
The problem may be caused by old cache. Sometimes, after an upgrade, the old cache might introduce strange, hard to debug behaviour such as unkillable shells, hangs when changing various settings, Ark being unable to extract archives or Amarok not recognizing any of your music. This solution can also resolve problems with KDE and Qt applications looking bad after an update.
Rebuild the cache using the following commands:
$ rm ~/.config/Trolltech.conf $ kbuildsycoca5 --noincremental
Optionally, empty the ~/.cache/ folder contents, however, this will also clear the cache of other applications:
$ rm -rf ~/.cache/*
Cannot change theme, icons, fonts, colors in systemsettings; most icons are not displayed
Make sure that QT_QPA_PLATFORMTHEME environment variable is unset, the command printenv QT_QPA_PLATFORMTHEME should show empty output. The variable is used normally to force qt5ct settings upon Qt applications.
Volume control, notifications or multimedia keys do not work
Hiding certain items in the System Tray settings (e.g. Audio Volume, Media Player or Notifications) also disables related features. Hiding the Audio Volume disables volume control keys, Media Player disables multimedia keys (rewind, stop, pause) and hiding Notifications disables showing notifications.
Login Screen KCM does not sync cursor settings to SDDM
The Login Screen KCM reads your cursor settings from ~/.config/kcminputrc, without this file no settings are synced. The easiest way to generate this file is to change your cursor theme in System Settings > Cursors, then change it back to your preferred cursor theme.
Missing panels/widgets
A crash or hardware change can modify the screen numbers, even on a single monitor setup. The panels/widgets can be missing after such an event, this can be fix in the ~/.config/plasma-org.kde.plasma.desktop-appletsrc file by changing the lastScreen values.
Graphical problems
Make sure you have the proper driver for your GPU installed. See Xorg#Driver installation for more information. If you have an older card, it might help to #Disable desktop effects manually or automatically for defined applications or #Disable compositing.
Getting current state of KWin for support and debug purposes
This command prints out a summary of the current state of KWin including used options, used compositing backend and relevant OpenGL driver capabilities. See more on Martin's blog.
$ qdbus org.kde.KWin /KWin supportInformation
Disable desktop effects manually or automatically for defined applications
Plasma has desktop effects enabled by default and e.g. not every game will disable them automatically. You can disable desktop effects in System Settings > Desktop Behavior > Desktop Effects and you can toggle desktop effects with Alt+Shift+F12.
Additionally, you can create custom KWin rules to automatically disable/enable compositing when a certain application/window starts under System Settings > Window Management > Window Rules.
Enable transparency
If you use a transparent background without enabling the compositor, you will get the message:
This color scheme uses a transparent background which does not appear to be supported on your desktop
In System Settings > Display and Monitor > Compositor, check Enable compositor on startup and restart Plasma.
Disable compositing
In System Settings > Display and Monitor > Compositor, uncheck Enable compositor on startup and restart Plasma.
Flickering in fullscreen when compositing is enabled
In System Settings > Display and Monitor > Compositor, uncheck Allow applications to block compositing. This may harm performance.
Screen tearing with NVIDIA
See NVIDIA/Troubleshooting#Avoid screen tearing in KDE (KWin).
Plasma cursor sometimes shown incorrectly
Create the directory ~/.icons/default and inside a file named index.theme with the following contents:
~/.icons/default/index.theme
[Icon Theme] Inherits=breeze_cursors
Execute the following command:
$ ln -s /usr/share/icons/breeze_cursors/cursors ~/.icons/default/cursors
Cursor jerking/flicking when changing roles (e.g., when mousing over hyperlinks)
Try installing the appropriate 2D acceleration driver for your system and window manager.
Unusable screen resolution set
Your local configuration settings for kscreen can override those set in xorg.conf. Look for kscreen configuration files in ~/.local/share/kscreen/ and check if mode is being set to a resolution that is not supported by your monitor.
Blurry icons in system tray
In order to add icons to tray, applications often make use of the library appindicator. If your icons are blurry, check which version of libappindicator you have installed. If you only have libappindicator-gtk2 installed, you can install libappindicator-gtk3 as an attempt to get clear icons.
Cannot change screen resolution when running in a virtual machine
When running Plasma in a VMware, VirtualBox or QEMU virtual machine, kscreen may not allow changing the guest's screen resolution to a resolution higher than 800×600.
The workaround is to set the PreferredMode option in xorg.conf.d(5). Alternatively try using a different graphics adapter in the VM, e.g. VBoxSVGA instead of VMSVGA for VirtualBox and Virtio instead of QXL for QEMU. See KDE Bug 407058 for details.
Sound problems
No sound after suspend
If there is no sound after suspending and if KMix does not show audio devices which should be there, restarting plasmashell and pulseaudio may help:
$ killall plasmashell $ systemctl --user restart pulseaudio.service $ plasmashell
Some applications may also need to be restarted in order for sound to play from them again.
MP3 files cannot be played when using the GStreamer Phonon backend
This can be solved by installing the GStreamer libav plugin (package gst-libav). If you still encounter problems, you can try changing the Phonon backend used by installing another such as phonon-qt4-vlcAUR or phonon-qt5-vlc.
Then, make sure the backend is preferred via System Settings > Multimedia > Audio and Video > Backend.
Power management
No Suspend/Hibernate options
If your system is able to suspend or hibernate using systemd but do not have these options shown in KDE, make sure powerdevil is installed.
KMail
Clean Akonadi configuration to fix KMail
See this document for detail.
If you want a backup, copy the following configuration directories:
$ cp -a ~/.local/share/akonadi ~/.local/share/akonadi-old $ cp -a ~/.config/akonadi ~/.config/akonadi-old
Empty IMAP inbox in KMail
For some IMAP accounts KMail will show the inbox as a top-level container (so it will not be possible to read messages there) with all other folders of this account inside.[8]. To solve this problem simply disable the server-side subscriptions in the KMail account settings.
Authorization error for EWS account in KMail
While setting up EWS account in KMail, you may keep getting errors about failed authorization even for valid and fully working credentials. This is likely caused by broken communication between KWallet and KMail. To workaround the issue set a passsword via qdbus:
$ qdbus org.freedesktop.Akonadi.Resource.akonadi_ews_resource_0 /Settings org.kde.Akonadi.Ews.Wallet.setPassword "XXX"
Networking
Freezes when using Automount on a NFS volume
Using Fstab#Automount with systemd on a NFS volume may cause freezes, see bug report upstream.
Aggressive QXcbConnection journal logging
See Qt#Disable/Change Qt journal logging behaviour.
KF5/Qt 5 applications do not display icons in i3/FVWM/awesome
See Qt#Configuration of Qt5 apps under environments other than KDE Plasma.
Problems with saving credentials and persistently occurring KWallet dialogs
It is not recommended to turn off the KWallet password saving system in the user settings as it is required to save encrypted credentials like WiFi passphrases for each user. Persistently occuring KWallet dialogs can be the consequence of turning it off.
In case you find the dialogs to unlock the wallet annoying when applications want to access it, you can let the display managers SDDM and LightDM unlock the wallet at login automatically, see KDE Wallet#Unlock KDE Wallet automatically on login. The first wallet needs to be generated by KWallet (and not user-generated) in order to be usable for system program credentials.
In case you want the wallet credentials not to be opened in memory for every application, you can restrict applications from accessing it with kwalletmanager in the KWallet settings.
If you do not care for credential encryption at all, you can simply leave the password forms blank when KWallet asks for the password while creating a wallet. In this case, applications can access passwords without having to unlock the wallet first.
Discover does not show any applications
This can be solved by installing packagekit-qt5.
High CPU usage of kscreenlocker_greet with NVIDIA drivers
As described in KDE Bug 347772 NVIDIA OpenGL drivers and QML may not play well together with Qt 5. This may lead kscreenlocker_greet to high CPU usage after unlocking the session. To work around this issue, set the QSG_RENDERER_LOOP environment variable to basic.
Then kill previous instances of the greeter with killall kscreenlocker_greet.
OS error 22 when running Akonadi on ZFS
If your home directory is on a ZFS pool, create a ~/.config/akonadi/mysql-local.conf file with the following contents:
[mysqld] innodb_use_native_aio = 0
See MariaDB#OS error 22 when running on ZFS.
Some programs are unable to scroll when their windows are inactive
This is caused by the problematic way of GTK3 handling mouse scroll events. A workaround for this is to set environment variable GDK_CORE_DEVICE_EVENTS=1. However, this workaround also breaks touchpad smooth scrolling and touchscreen scrolling.
TeamViewer behaves slowly
When using TeamViewer, it may behave slowly if you use smooth animations (such as windows minimizing). See #Disable compositing as a workaround.
Kmail, Kontact and wayland
Kmail may become unresponsive, show a black messageviewer or similar, often after having been minimized and restored. A workaround may be to set environment variable QT_QPA_PLATFORM="xcb;wayland".