Ubuntu: Search fields respond slowly to input on Plasma KDE desktop


I'm on a upgraded version of Kubuntu, from 16.04 to 17.04 and then to 17.10.

When trying to type something in krunner or in a search field of the application menu - the letters just don't appear as typed.

Sometimes letters appear after having typed them several times.
But neither Konsole or Browser, or even text editors are affected, only search fields in krunner and the application menu.

Update: After some time (and several updates) more input fields started to misbehave:

  • password entry field in network manager
  • search in application launcher

System details:

Lenovo X1 Carbon Gen 3

Output of qtdiag:

  Qt 5.9.1 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 7.2.0) on "xcb"   OS: Ubuntu 17.10 [linux version 4.13.0-32-generic]    Architecture: x86_64; features: SSE2 SSE3 SSSE3 SSE4.1 SSE4.2 AVX AVX2 RTM HLE    Environment:    QT4_IM_MODULE="ibus"    QT_ACCESSIBILITY="1"    QT_AUTO_SCREEN_SCALE_FACTOR="0"    QT_IM_MODULE="ibus"    QT_QPA_PLATFORMTHEME="appmenu-qt5"    QT_QUICK_CONTROLS_STYLE="org.kde.desktop"    Features: QT_NO_EXCEPTIONS    Library info:    PrefixPath: /usr    DocumentationPath: /usr/share/qt5/doc    HeadersPath: /usr/include/x86_64-linux-gnu/qt5    LibrariesPath: /usr/lib/x86_64-linux-gnu    LibraryExecutablesPath: /usr/lib/x86_64-linux-gnu/qt5/libexec    BinariesPath: /usr/lib/x86_64-linux-gnu/qt5/bin    PluginsPath: /usr/lib/x86_64-linux-gnu/qt5/plugins    ImportsPath: /usr/lib/x86_64-linux-gnu/qt5/imports    Qml2ImportsPath: /usr/lib/x86_64-linux-gnu/qt5/qml    ArchDataPath: /usr/lib/x86_64-linux-gnu/qt5    DataPath: /usr/share/qt5    TranslationsPath: /usr/share/qt5/translations    ExamplesPath: /usr/lib/x86_64-linux-gnu/qt5/examples    TestsPath: /usr/tests    SettingsPath: /etc/xdg    Standard paths [*...* denote writable entry]:    DesktopLocation: "Desktop" */home/USERNAME/Desktop*    DocumentsLocation: "Documents" */home/USERNAME/Documents*    FontsLocation: "Fonts" */home/USERNAME/.local/share/fonts* /home/USERNAME/.fonts    ApplicationsLocation: "Applications" */home/USERNAME/.local/share/applications* /usr/share/usr/share/xsessions/plasma/applications /usr/local/share/applications /usr/share/applications /var/lib/snapd/desktop/applications    MusicLocation: "Music" */home/USERNAME/Music*    MoviesLocation: "Movies" */home/USERNAME/Videos*    PicturesLocation: "Pictures" */home/USERNAME/Pictures*    TempLocation: "Temporary Directory" */tmp*    HomeLocation: "Home" */home/USERNAME*    AppLocalDataLocation: "Application Data" */home/USERNAME/.local/share/QtProject/qtdiag* /usr/share/usr/share/xsessions/plasma/QtProject/qtdiag /usr/local/share/QtProject/qtdiag /usr/share/QtProject/qtdiag /var/lib/snapd/desktop/QtProject/qtdiag    CacheLocation: "Cache" */home/USERNAME/.cache/QtProject/qtdiag*    GenericDataLocation: "Shared Data" */home/USERNAME/.local/share* /usr/share/usr/share/xsessions/plasma /usr/local/share /usr/share /var/lib/snapd/desktop    RuntimeLocation: "Runtime" */run/user/1000*    ConfigLocation: "Configuration" */home/USERNAME/.config* /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg /usr/share/kubuntu-default-settings/kf5-settings    DownloadLocation: "Download" */home/USERNAME/Downloads*    GenericCacheLocation: "Shared Cache" */home/USERNAME/.cache*    GenericConfigLocation: "Shared Configuration" */home/USERNAME/.config* /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg/xdg-/usr/share/xsessions/plasma /etc/xdg /usr/share/kubuntu-default-settings/kf5-settings    AppDataLocation: "Application Data" */home/USERNAME/.local/share/QtProject/qtdiag* /usr/share/usr/share/xsessions/plasma/QtProject/qtdiag /usr/local/share/QtProject/qtdiag /usr/share/QtProject/qtdiag /var/lib/snapd/desktop/QtProject/qtdiag    AppConfigLocation: "Application Configuration" */home/USERNAME/.config/QtProject/qtdiag* /etc/xdg/xdg-/usr/share/xsessions/plasma/QtProject/qtdiag /etc/xdg/xdg-/usr/share/xsessions/plasma/QtProject/qtdiag /etc/xdg/QtProject/qtdiag /usr/share/kubuntu-default-settings/kf5-settings/QtProject/qtdiag    File selectors (increasing order of precedence):    en_US unix linux ubuntu    Network:    Using "OpenSSL 1.0.2g  1 Mar 2016", version: 0x1000207f    Platform capabilities: ThreadedPixmaps OpenGL WindowMasks MultipleWindows ForeignWindows NonFullScreenWindows NativeWidgets WindowManagement SyncState RasterGLSurface SwitchableWidgetComposition    Style hints:    mouseDoubleClickInterval: 300    mousePressAndHoldInterval: 800    startDragDistance: 4    startDragTime: 300    startDragVelocity: 0    keyboardInputInterval: 400    keyboardAutoRepeatRate: 30    cursorFlashTime: 1000    showIsFullScreen: 0    showIsMaximized: 0    passwordMaskDelay: 0    passwordMaskCharacter: U+25CF    fontSmoothingGamma: 1.7    useRtlExtensions: 0    setFocusOnTouchRelease: 0    tabFocusBehavior: Qt::TabFocusBehavior(TabFocusAllControls)     singleClickActivation: 0    Additional style hints (QPlatformIntegration):    ReplayMousePressOutsidePopup: 0    Theme:    Platforms requested : kde,generic              available : kde,gtk3    Styles requested    : oxygen,breeze,fusion,windows           available    : Breeze,Oxygen,Windows,Fusion    Icon theme          : breeze, hicolor from /home/USERNAME/.icons,/usr/share/icons    System font         : "Noto Sans" 12    Fonts:    General font : "Noto Sans" 12    Fixed font   : "Hack" 9    Title font   : "Noto Sans" 12    Smallest font: "Noto Sans" 8    Palette:    WindowText: #ff31363b    Button: #ffeff0f1    Light: #ffffffff    Midlight: #fff7f7f8    Dark: #ff888e93    Mid: #ffc4c9cd    Text: #ff31363b    BrightText: #ffffffff    ButtonText: #ff31363b    Base: #fffcfcfc    Window: #ffeff0f1    Shadow: #ff474a4c    Highlight: #ff3daee9    HighlightedText: #ffeff0f1    Link: #ff2980b9    LinkVisited: #ff7f8c8d    AlternateBase: #ffeff0f1    NoRole: #ff000000    ToolTipBase: #ff31363b    ToolTipText: #ffeff0f1    Screens: 1, High DPI scaling: inactive  # 0 "eDP-1" Depth: 24 Primary: yes    Manufacturer:     Model:     Serial number:     Geometry: 2560x1440+0+0 Available: 2560x1384+0+0    Physical size: 310x170 mm  Refresh: 59 Hz Power state: 0    Physical DPI: 209.755,215.153 Logical DPI: 120,120 Subpixel_None    DevicePixelRatio: 1 Pixel density: 2    Primary orientation: 2 Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0    Touch devices: 1    TouchPad "SynPS/2 Synaptics TouchPad", max 1 touch points, capabilities: Pressure MouseEmulation      LibGL Vendor: Intel Open Source Technology Center  Renderer: Mesa DRI Intel(R) HD Graphics 520 (Skylake GT2)   Version: 3.0 Mesa 17.2.8  Shading language: 1.30  Format: Version: 3.0 Profile: 0 Swap behavior: 0 Buffer size (RGB): 8,8,8    


The Lenovo X1 carbon gen 3 computer should have enough horsepower to run Kubuntu :-)

I suspect some mismatch because of the upgrading. Please try a live system, and if it works well, backup your personal files and make a fresh installation.

See the following link (and links from it),

Try Ubuntu (Kubuntu, Lubuntu, Xubuntu, ...) before installing it


If you have problems starting from the 16.04.3 iso file (maybe appearing after update & upgrade), you can try starting from the 16.04.1 iso file, that you find via this link (scroll down ...),


When you start from the 16.04.1 iso file, the kernel will stay within the linux 4.4 kernel series, the 'xenial kernel'.

You can also try the newest version, 17.10.1 from


or the still developing 'bionic' version, to be released as the next version with long time support in April 2018. This may work well, but it is a bit adventurous because many things are still in the development phase and there may be temporary bugs.

Kubuntu Desktop amd64 testcases in Bionic Daily of the QA-tracker

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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