After 11-18 stable update, KDE systemsettings can't be opened

After 11-18 stable update, KDE systemsettings can’t be opened. I can’t open discover either. If I run systemsettings5 in the terminal, I get the error

Cyclic dependency detected between "file:///usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml" and "file:///usr/lib/qt/qml/org/kde/kirigami.2/styles/org.kde.desktop.plasma/Units.qml"

I get the same error if I open plasma-discover in the terminal. I never met this problem before. There are some discussion related to this error in the forum. But I don’t find them very helpful.

11-22 update does not fix it. Any ideas?

Did you check tht the file Units.qml exists? I checked the file and don’t see any reference to dependencies. Odd that error “between” is referencing the same file.

Yes, this file exists. This is the content.

/*
    SPDX-FileCopyrightText: 2015 Marco Martin <mart@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

import QtQuick 2.4
import QtQuick.Window 2.2
import org.kde.plasma.core 2.0 as PlasmaCore
import QtQuick.Controls 1.4 as QtQuickControls
import QtQuick.Controls.Private 1.0 as QtQuickControlsPrivate
import org.kde.kirigami 2.4

pragma Singleton


/**
 * A set of values to define semantically sizes and durations
 * @inherit QtQuick.QtObject
 */
QtObject {
    id: unitsRoot

    /**
     * The fundamental unit of space that should be used for sizes, expressed in pixels.
     * Given the screen has an accurate DPI settings, it corresponds to a width of
     * the capital letter M
     */
    property int gridUnit: fontMetrics.height

    /**
     * units.iconSizes provides access to platform-dependent icon sizing
     *
     * The icon sizes provided are normalized for different DPI, so icons
     * will scale depending on the DPI.
     *
     * Icon sizes from KIconLoader, adjusted to devicePixelRatio:
     * * small
     * * smallMedium
     * * medium
     * * large
     * * huge
     * * enormous
     *
     * Not devicePixelRation-adjusted::
     * * desktop
     */
    property QtObject iconSizes: QtObject {
        property int small: Math.floor(fontMetrics.roundedIconSize(16 * devicePixelRatio) * (Settings.isMobile ? 1.5 : 1))
        property int smallMedium: Math.floor(fontMetrics.roundedIconSize(22 * devicePixelRatio) * (Settings.isMobile ? 1.5 : 1))
        property int medium: Math.floor(fontMetrics.roundedIconSize(32 * devicePixelRatio) * (Settings.isMobile ? 1.5 : 1))
        property int large: Math.floor(fontMetrics.roundedIconSize(48 * devicePixelRatio) * (Settings.isMobile ? 1.5 : 1))
        property int huge: Math.floor(fontMetrics.roundedIconSize(64 * devicePixelRatio) * (Settings.isMobile ? 1.5 : 1))
        property int enormous: Math.floor(128 * devicePixelRatio * (Settings.isMobile ? 1.5 : 1))
    }

    /**
     * units.smallSpacing is the amount of spacing that should be used around smaller UI elements,
     * for example as spacing in Columns. Internally, this size depends on the size of
     * the default font as rendered on the screen, so it takes user-configured font size and DPI
     * into account.
     */
    property int smallSpacing: Math.floor(gridUnit/4)

    /**
     * units.largeSpacing is the amount of spacing that should be used inside bigger UI elements,
     * for example between an icon and the corresponding text. Internally, this size depends on
     * the size of the default font as rendered on the screen, so it takes user-configured font
     * size and DPI into account.
     */
    property int largeSpacing: smallSpacing * 2

    /**
     * The ratio between physical and device-independent pixels. This value does not depend on the \
     * size of the configured font. If you want to take font sizes into account when scaling elements,
     * use theme.mSize(theme.defaultFont), units.smallSpacing and units.largeSpacing.
     * The devicePixelRatio follows the definition of "device independent pixel" by Microsoft.
     */
    property real devicePixelRatio: Math.max(1, ((fontMetrics.font.pixelSize*0.75) / fontMetrics.font.pointSize))

    /**
     * units.longDuration should be used for longer, screen-covering animations, for opening and
     * closing of dialogs and other "not too small" animations
     */
    property int longDuration: units.longDuration

    /**
     * units.shortDuration should be used for short animations, such as accentuating a UI event,
     * hover events, etc..
     */
    property int shortDuration: units.shortDuration

    /**
     * units.veryLongDuration should be used for specialty animations that benefit
     * from being even longer than longDuration.
     */
    property int veryLongDuration: units.veryLongDuration

    readonly property QtObject __styleItem: QtQuickControlsPrivate.StyleItem {elementType: "frame" }

    /**
     * How much the mouse scroll wheel scrolls, expressed in lines of text.
     * Note: this is strictly for classical mouse wheels, touchpads 2 figer scrolling won't be affected
     */
    readonly property int wheelScrollLines: __styleItem.styleHint("wheelScrollLines")

    /**
     * time in ms by which the display of tooltips will be delayed.
     *
     * @sa ToolTip.delay property
     */
    property int toolTipDelay: 700

    /**
     * metrics used by the default font
     */
    property variant fontMetrics: TextMetrics {
        text: "M"
        function roundedIconSize(size) {
            if (size < 16) {
                return size;
            } else if (size < 22) {
                return 16;
            } else if (size < 32) {
                return 22;
            } else if (size < 48) {
                return 32;
            } else if (size < 64) {
                return 48;
            } else {
                return size;
            }
        }
    }
}

By reinstall kirigami2, I can open systemsettings again.