简而言之：
我有同样的问题，正如所描述的那样这里。然而，建议的解决方案对我不起作用。
我设法杀死plasmashellvia killall plasmashell，然后可以使用命令手动重新启动它plasmashell。
这样做会导致我的屏幕上弹出以下消息：
ddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
No metadata file in the package, expected it at: "/usr/share/backgrounds/linuxmint-sylvia/"
No metadata file in the package, expected it at: "/usr/share/backgrounds/linuxmint-sylvia/"
No metadata file in the package, expected it at: "/usr/share/backgrounds/linuxmint-sylvia/"
trying to show an empty dialog
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:147:19: QML Loader: Binding loop detected for property "height"
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:147:19: QML Loader: Binding loop detected for property "height"
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Panel.qml:83: TypeError: Cannot read property 'Layout' of null
Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/main.qml:112:20: Unable to assign [undefined] to int
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
Trying to use rootObject before initialization is completed, whilst using setInitializationDelayed. Forcing completion
file:///usr/share/plasma/plasmoids/org.kde.plasma.digitalclock/contents/ui/main.qml:78:27: Unable to assign [undefined] to QStringList
file:///usr/share/plasma/plasmoids/org.kde.plasma.digitalclock/contents/ui/main.qml:37: TypeError: Cannot read property 'DateTime' of undefined
trying to show an empty dialog
trying to show an empty dialog
trying to show an empty dialog
file:///usr/share/plasma/plasmoids/org.kde.plasma.digitalclock/contents/ui/DigitalClock.qml:443:5: QML Text: Cannot anchor to a null item.
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
kf5.kcoreaddons.desktopparser: Could not locate service type file kservicetypes5/plasma-popupapplet.desktop, tried ("/home/<userName>/.local/share", "/home/<userName>/.local/share/flatpak/exports/share", "/var/lib/flatpak/exports/share", "/usr/share/usr/share/xsessions/plasma", "/usr/local/share", "/usr/share")
我相信其中大部分都不太重要，但我想以下几行与我的问题有关：尝试显示一个空对话框
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:147:19: QML Loader: Binding loop detected for property "height"
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:147:19: QML Loader: Binding loop detected for property "height"
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Panel.qml:83: TypeError: Cannot read property 'Layout' of null
对我来说，这表明在某个时刻传递/创建了一些无效数据，导致此处出现空值，（我相信）这是桌面无法正常运行的根本原因。
更长的故事：
所以我在我的笔记本电脑上安装了 Linux Mint 19，并在上面安装了 KDE。一切都工作得很好。
今天，我继续在笔记本电脑的另一个分区上安装了 KDE neon，（理论上）Mint 分区完全保持不变。
发生变化的是我的 EFI 分区和两个系统共享的交换分区。
似乎 KDE Neon 安装已经完全覆盖了我从 Mint 获得的 GRUB 加载程序（通过 BIOS，我可以选择每个系统的加载程序，但两者都会产生完全相同的引导加载程序，所以我相信 Neon 只是覆盖了 Mint 的加载程序） 。
不过我可以正常启动 Mint。唯一的问题是，当我登录时，启动屏幕比之前要花更长的时间，之后我进入桌面，现在错过了开始菜单和完整的任务栏。他们就这样走了。右键单击我的桌面也没有任何反应。
尽管我可以在桌面上看到所有快捷方式，但我无法单击其中任何一个（更准确地说：我可以单击它们，但没有任何反应）。
编辑：
我更多地考虑了这个问题：当安装程序格式化引导分区时，它也删除了已安装的内核。所以问题可能是 KDE-Neon 内核与 Linux Mint 系统不完全兼容，这会导致一些问题。我将进一步调查此事...
答案1
您的问题可能是由 KDE-Neon 覆盖主目录中的桌面配置文件（'/home/Your_User/.config/plasma-org.kde.plasma.desktop-appletsrc'）引起的。
当您单击快捷方式时，它们会引用如下小程序定义：
[Containments][23][Applets][48][Configuration]
PreloadWeight=0
localPath=/home/me/.local/share/plasma_icons/chromium-browser.desktop
url=file:///usr/share/applications/chromium-browser.desktop
您的“url=file:///”已更改为引用 neon 分区的挂载点，该挂载点在您加载 mint 时并不存在。
如果您在安装 Neon 之前有该文件的备份，请使用旧文件覆盖 Neon 安装的更改。如果您不这样做...您可以手动编辑该文件。或者，您可能必须删除所有内容并重新构建它（新面板、新桌面快捷方式）。对不起！但要小心使用相同的软件运行不同的发行版，共享相同的主分区和目录。始终先备份。
当尝试新的“实时”发行版时，您还可以在 /home 中创建一个新的 UserID - 以新用户身份登录（使用空配置文件）。使用此方法，Live Distro 会将其默认配置文件写入新的用户 ID，而不是覆盖您的生产“用户”信息。
以下是 Mageia 的“live DVD”警告部分的一段文字，描述了他们自己的“Live”媒体版本的问题：
警告！ 如果您不格式化 /home 分区，请使用新登录名创建用户。用户的配置写入用户空间，可以覆盖一些个人数据。 Firefox、Thunderbird、Kmail 数据可能就是这种情况......
...这也将适用于您的 .config 设置。
您将 Neon 安装在单独的分区中（包含系统根目录“/”、“/var”、“/usr”和 swap）。但是，与 Magiea-Live 一样，如果它识别出现有的 /home 分区并且您使用它（通过已配置的现有登录名）...它将编辑并覆盖您的 Mint UserID 配置中的文件。
稍微有点过时：KDE-NEON 无法在不破坏其他发行版的 GRUB2 信息的情况下“安装”，这似乎“不友好”……但这与 .config 覆盖是不同的问题。