Desktop notifications

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Desktop notifications are small, passive popup dialogs that notify the user of particular events in an asynchronous manner.

Libnotify

Libnotify is an implementation of the Desktop Notifications Specification which provides support for GTK and Qt applications and is desktop independent: it is already used by many open source apps like Evolution and Pidgin. Libnotify can be installed with the libnotify package.

In order to use libnotify, you have to install a notification server.

Notification servers

Built-in

Cinnamon, Deepin, Enlightenment, GNOME, GNOME Flashback and KDE Plasma use their own implementations to display notifications, and it cannot be replaced. Their notification servers are started automatically on login to receive notifications from applications via DBus.

Standalone

In other desktop environments, the notification server needs to be launched using an autostarting option.

Alternatively, making the notification server as a D-Bus service, the notification server can be launched automatically on the first call to it. For example, after installing the notification-daemon package, add the following configuration to D-Bus services directory (/usr/share/dbus-1/services or $XDG_DATA_HOME/dbus-1/services):

org.freedesktop.Notifications.service
[D-BUS Service]
Name=org.freedesktop.Notifications
Exec=/usr/lib/notification-daemon-1.0/notification-daemon

Whenever an application sends a notification by sending a signal to org.freedesktop.Notifications, D-Bus activates /usr/lib/notification-daemon-1.0/notification-daemon if it has not already been activated.

You can also choose one of the following implementations:

https://github.com/p12tic/awn-extras || awn-extras-appletsAUR
  • Deadd Notification Center — A notification-daemon with notification center inspired by Dunst.
https://github.com/phuhl/linux_notification_center || deadd-notification-centerAUR
  • Dunst — Minimalist notification daemon for Linux designed to fit nicely into minimalist window managers like dwm. Includes Wayland support since 1.6.
https://dunst-project.org/ || dunst
  • fnott — Keyboard driven and lightweight Wayland notification daemon for wlroots-based compositors.
https://codeberg.org/dnkl/fnott || fnottAUR
  • LXQt Notification Daemon — Notification server for LXQt.
https://github.com/lxde/lxqt-notificationd || lxqt-notificationd
  • mako — A lightweight notification daemon for Wayland; it currently works on Sway.
https://github.com/emersion/mako || mako
  • MATE Notification Daemon — Notification server for MATE.
https://github.com/mate-desktop/mate-notification-daemon/ || mate-notification-daemon
  • Notification Daemon — The original notification server.
https://gitlab.gnome.org/Archive/notification-daemon || notification-daemon
You can run it manually using /usr/lib/notification-daemon-1.0/notification-daemon.
  • Notify OSD — Notification server for Unity.
https://launchpad.net/notify-osd || notify-osd
  • statnot — Small, lightweight notification daemon that can output notifications to the root window's title, stdout or FIFO pipes, making it integrate very well with tiling window managers.
https://github.com/halhen/statnot || statnotAUR
  • sandsmark-notificationd — Minimalistic notification-daemon with muting support.
https://github.com/sandsmark/sandsmark-notificationd || sandsmark-notificationd-gitAUR
  • twmn — Notification system for tiling window managers.
https://github.com/sboli/twmn || twmn-gitAUR
  • wired — Lightweight notification daemon with highly customizable layout blocks, written in Rust.
https://github.com/Toqozz/wired-notify || wiredAUR
  • Xfce Notification Daemon — Notification server for Xfce.
https://docs.xfce.org/apps/notifyd/start || xfce4-notifyd
You can run it manually using /usr/lib/xfce4/notifyd/xfce4-notifyd.
Tip: To configure xfce4-notifyd, run the following command: xfce4-notifyd-config.

Usage in programming

You can write your own libnotify display messages easily in many programming languages through GObject-Introspection or bindings, or you can simply use bash.

The following examples display a simple "Hello world" notification.

Bash

hello_world.sh
#!/bin/bash
notify-send 'Hello world!' 'This is an example notification.' --icon=dialog-information
Tip:
  • An overview on the available icons can be found here.
  • To send desktop notification from a background script running as root (replace X_user and X_userid with the user and userid running X respectively):
    # sudo -u X_user DISPLAY=:0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/X_userid/bus notify-send 'Hello world!' 'This is an example notification.'
hello_world.sh
#!/bin/bash
gdbus call --session \
    --dest=org.freedesktop.Notifications \
    --object-path=/org/freedesktop/Notifications \
    --method=org.freedesktop.Notifications.Notify \
    "" 0 "" 'Hello world!' 'This is an example notification.' \
    '[]' '{"urgency": <1>}' 5000
Tip:
  • See org.freedesktop.Notifications.Notify for more details about the D-Bus interface.
  • dbus-send, though being similar to gdbus, does not work because one of the arguments in the method org.freedesktop.Notifications.Notify requires data type variant, which is not supported by dbus-send.

Boo

  • Dependency: notify-sharp-3 (booAUR)
  • Makedependency: booAUR
  • Build with: booc hello_world.boo
  • Run with: mono hello_world.exe (or booi hello_world.boo)
hello_world.boo
import Notifications from "notify-sharp"
Hello = Notification()
Hello.Summary  = "Hello world!"
Hello.Body     = "This is an example notification."
Hello.IconName = "dialog-information"
Hello.Show()

C

  • Dependency: glib2
  • Build with: gcc -o hello_world `pkg-config --cflags --libs gio-2.0` hello_world.c
hello_world.c
#include <gio/gio.h>
int main() {
	GApplication *application = g_application_new ("hello.world", G_APPLICATION_FLAGS_NONE);
	g_application_register (application, NULL, NULL);
	GNotification *notification = g_notification_new ("Hello world!");
	g_notification_set_body (notification, "This is an example notification.");
	GIcon *icon = g_themed_icon_new ("dialog-information");
	g_notification_set_icon (notification, icon);
	g_application_send_notification (application, NULL, notification);
	g_object_unref (icon);
	g_object_unref (notification);
	g_object_unref (application);
	return 0;
}
  • Dependency: libnotify
  • Build with: gcc -o hello_world `pkg-config --cflags --libs libnotify` hello_world.c
hello_world.c
#include <libnotify/notify.h>
int main() {
	notify_init ("Hello world!");
	NotifyNotification * Hello = notify_notification_new ("Hello world", "This is an example notification.", "dialog-information");
	notify_notification_show (Hello, NULL);
	g_object_unref(G_OBJECT(Hello));
	notify_uninit();
	return 0;
}
  • Dependency: dbus
  • Build with: gcc -o hello_world $(pkg-config --cflags --libs dbus-1) hello_world.c
hello_world.c
#include <dbus-1.0/dbus/dbus.h>
int main()
{
	DBusConnection *connection = dbus_bus_get(DBUS_BUS_SESSION, 0);
	DBusMessage *message = dbus_message_new_method_call(
		"org.freedesktop.Notifications",
		"/org/freedesktop/Notifications",
		"org.freedesktop.Notifications",
		"Notify");
	DBusMessageIter iter[4];
	dbus_message_iter_init_append(message, iter);
	char *application = "hello.world";
	dbus_message_iter_append_basic(iter, 's', &application);
	unsigned id = 0;
	dbus_message_iter_append_basic(iter, 'u', &id);
	char *icon = "dialog-information";
	dbus_message_iter_append_basic(iter, 's', &icon);
	char *summary = "Hello world!";
	dbus_message_iter_append_basic(iter, 's', &summary);
	char *body = "This is an example notification.";
	dbus_message_iter_append_basic(iter, 's', &body);
	dbus_message_iter_open_container(iter, 'a', "s", iter + 1);
	dbus_message_iter_close_container(iter, iter + 1);
	dbus_message_iter_open_container(iter, 'a', "{sv}", iter + 1);
	dbus_message_iter_open_container(iter + 1, 'e', 0, iter + 2);
	char *urgency = "urgency";
	dbus_message_iter_append_basic(iter + 2, 's', &urgency);
	dbus_message_iter_open_container(iter + 2, 'v', "y", iter + 3);
	enum {LOW, NORMAL, CRITICAL};
	unsigned char level = LOW;
	dbus_message_iter_append_basic(iter + 3, 'y', &level);
	dbus_message_iter_close_container(iter + 2, iter + 3);
	dbus_message_iter_close_container(iter + 1, iter + 2);
	dbus_message_iter_close_container(iter, iter + 1);
	int timeout = 5 * 1000;
	dbus_message_iter_append_basic(iter, 'i', &timeout);
	dbus_connection_send(connection, message, 0);
	dbus_connection_flush(connection);
	dbus_message_unref(message);
	dbus_connection_unref(connection);
}

C++

  • Dependency: glibmm
  • Build with: g++ -o hello_world `pkg-config --cflags --libs giomm-2.4` hello_world.cc
hello_world.cc
#include <giomm-2.4/giomm.h>
int main(int argc, char *argv[]) {
	auto Application = Gio::Application::create("hello.world", Gio::APPLICATION_FLAGS_NONE);
	Application->register_application();
	auto Notification = Gio::Notification::create("Hello world");
	Notification->set_body("This is an example notification.");
	auto Icon = Gio::ThemedIcon::create("dialog-information");
	Notification->set_icon (Icon);
	Application->send_notification(Notification);
	return 0;
}
  • Dependency: libnotifymmAUR
  • Build with: g++ -o hello_world `pkg-config --cflags --libs libnotifymm-1.0` hello_world.cc
hello_world.cc
#include <libnotifymm.h>
int main(int argc, char *argv[]) {
	Notify::init("Hello world!");
	Notify::Notification Hello("Hello world", "This is an example notification.", "dialog-information");
	Hello.show();
	return 0;
}

C#

  • Dependency: notify-sharp-3
  • Build with: mcs -pkg:notify-sharp-3.0 hello_world.cs
  • Run with: mono hello_world.exe
hello_world.cs
using Notifications;
public class HelloWorld {
	static void Main() {
		var Hello = new Notification();
		Hello.Summary  = "Hello world!";
		Hello.Body     = "This is an example notification.";
		Hello.IconName = "dialog-information";
		Hello.Show();
	}
}

Cobra

hello_world.cobra
@args -pkg:notify-sharp-3.0
use Notifications
class HelloWorld
    def main
        hello = Notification()
        hello.summary  = "Hello world!"
        hello.body     = "This is an example notification."
        hello.iconName = "dialog-information"
        hello.show

Crystal

  • Dependency: woodruffw/notify.cr (from shards)
  • Build with: shards build
hello_world.fs
require "notify"
notifier = Notify.new
notifier.notify "Hello", body: "World!"

F#

  • Dependency: notify-sharp-3
  • Makedependency: dotnet-sdk
  • Build with: fsharpc -r:notify-sharp.dll -I:/usr/lib/mono/notify-sharp-3.0/ -I:/usr/lib/mono/gtk-sharp-3.0/ hello_world.fs
  • Run with: mono hello_world.exe
hello_world.fs
open Notifications
let Hello = new Notification()
Hello.Summary  <- "Hello world!"
Hello.Body     <- "This is an example notification."
Hello.IconName <- "dialog-information"
Hello.Show()

Genie

  • Dependency: glib2
  • Makedependency: vala
  • Build with: valac --pkg gio-2.0 hello_world.gs
hello_world.gs
uses 
	GLib

init
	var Application = new GLib.Application ("hello.world", GLib.ApplicationFlags.FLAGS_NONE);
	Application.register ();
	var Notification = new GLib.Notification ("Hello world");
	Notification.set_body ("This is an example notification.");
	var Icon = new GLib.ThemedIcon ("dialog-information");
	Notification.set_icon (Icon);
	Application.send_notification (null, Notification);
  • Dependency: libnotify
  • Makedependency: vala
  • Build with: valac --pkg libnotify hello_world.gs
hello_world.gs
uses 
	Notify

init
	Notify.init ("Hello world")
	var Hello=new Notify.Notification ("Hello world!","This is an example notification.","dialog-information")
	Hello.show ()

Go

  • Dependency: libnotify
  • Makedependency: go-notify-gitAUR
  • Build with: go build hello_world.go
  • (Or run with: go run hello_world.go)
hello_world.go
package main
import ("github.com/mqu/go-notify")

func main() {
	notify.Init("Hello world")
	hello := notify.NotificationNew("Hello World!", "This is an example notification.","dialog-information")
	hello.Show()
}

Groovy

  • Dependencies: groovy, java-gnomeAUR
  • Build with: groovyc -cp /usr/share/java/gtk.jar HelloWorld.groovy && jar cfe HelloWorld.jar HelloWorld HelloWorld.class
  • Run with: java -cp /usr/share/groovy/embeddable/groovy-all.jar:/usr/share/java/gtk.jar:HelloWorld.jar HelloWorld or groovy -cp /usr/share/java/gtk.jar HelloWorld.groovy
HelloWorld.groovy
import org.gnome.gtk.*
import org.gnome.notify.*

Gtk.init()
Notify.init("Hello world")
def Hello = new Notification("Hello world!", "This is an example notification.", "dialog-information")
Hello.show()

Haskell

hello_world.hs
import DBus.Notify
main = do
         client <- connectSession
         let hello = blankNote { summary="Hello world!",
                                 body=(Just $ Text "This is an example notification."),
                                 appImage=(Just $ Icon "dialog-information") }
         notification <- notify client hello
         return 0

IronPython

hello_world.py
import clr
clr.AddReference('notify-sharp')
import Notifications
Hello = Notifications.Notification()
Hello.Summary  = "Hello world!"
Hello.Body     = "This is an example notification."
Hello.IconName = "dialog-information"
Hello.Show()

Java

  • Dependency: java-gnomeAUR
  • Makedependency: java-environment
  • Build with: javac -cp /usr/share/java/gtk.jar HelloWorld.java && jar cfe HelloWorld.jar HelloWorld HelloWorld.class
  • Run with: java -cp /usr/share/java/gtk.jar:HelloWorld.jar HelloWorld
HelloWorld.java
import org.gnome.gtk.Gtk;
import org.gnome.notify.Notify;
import org.gnome.notify.Notification;

public class HelloWorld
{
    public static void main(String[] args) {
        Gtk.init(args);
        Notify.init("Hello world");
        Notification Hello = new Notification("Hello world!", "This is an example notification.", "dialog-information");
        Hello.show();
    }
}

JavaScript

  • Dependency: gjs
hello_world.js
#!/usr/bin/gjs
const Gio = imports.gi.Gio;
var Application = new Gio.Application ({application_id: "hello.world"});
Application.register (null);
var Notification = new Gio.Notification ();
Notification.set_title ("Hello world");
Notification.set_body ("This is an example notification.");
var Icon = new Gio.ThemedIcon ({name: "dialog-information"});
Notification.set_icon (Icon);
Application.send_notification (null, Notification);
hello_world.js
#!/usr/bin/gjs
const Notify = imports.gi.Notify;
Notify.init ("Hello world");
var Hello=new Notify.Notification ({summary: "Hello world!",
                                    body: "This is an example notification.",
                                    "icon-name": "dialog-information"});
Hello.show ();

JRuby

  • Dependencies: java-gnomeAUR, jruby
  • Build with: jrubyc hello_world.rb && jar cfe hello_world.jar hello_world hello_world.class
  • Run with: java -cp /opt/jruby/lib/jruby.jar:hello_world.jar hello_world or jruby hello_world.rb
hello_world.rb
require '/usr/share/java/gtk.jar'
import Java::OrgGnomeGtk::Gtk
import Java::OrgGnomeNotify::Notify
import Java::OrgGnomeNotify::Notification

Gtk.init(nil)
Notify.init("Hello world")
Hello = Notification.new("Hello world!", "This is an example notification.", "dialog-information")
Hello.show

Jython

  • Dependencies: java-gnomeAUR, jython
  • Run with: jython -Dpython.path=/usr/share/java/gtk.jar hello_world.py
hello_world.py
from org.gnome.gtk import Gtk
from org.gnome.notify import Notify, Notification
Gtk.init(None)
Notify.init("Hello world")
Hello=Notification("Hello world!", "This is an example notification.", "dialog-information")
Hello.show()

Lua

hello_world.lua
#!/usr/bin/lua
lgi = require 'lgi'
Gio = lgi.require('Gio')
Application = Gio.Application.new("hello.world",Gio.ApplicationFlags.FLAGS_NONE);
Application:register();
Notification = Gio.Notification.new("Hello world");
Notification:set_body("This is an example notification.");
Icon = Gio.ThemedIcon.new("dialog-information");
Notification:set_icon(Icon);
Application:send_notification(nil, Notification);
hello_world.lua
#!/usr/bin/lua
lgi = require 'lgi'
Notify = lgi.require('Notify')
Notify.init("Hello world")
Hello=Notify.Notification.new("Hello world","This is an example notification.","dialog-information")
Hello:show()

Nemerle

  • Dependency: notify-sharp-3
  • Makedependency: nemerleAUR
  • Build with: ncc -pkg:notify-sharp-3.0 -out:hello_world.exe hello_world.n
  • Run with: mono hello_world.exe
hello_world.n
using Notifications;
public class HelloWorld {
	static Main() : void {
		def Hello = Notification();
		Hello.Summary  = "Hello world!";
		Hello.Body     = "This is an example notification.";
		Hello.IconName = "dialog-information";
		Hello.Show();
	}
}

Pascal

hello_world.pas
program	hello_world;
uses	libnotify;
var	hello : PNotifyNotification;
begin
	notify_init(argv[0]);
	hello := notify_notification_new ('Hello world', 'This is an example notification.', 'dialog-information');
	notify_notification_show (hello, nil);
end.

Perl

Using libnotify

hello_world.pl
#!/usr/bin/perl
use Glib::Object::Introspection;
Glib::Object::Introspection->setup(basename => 'Notify',
                                   version => '0.7',
                                   package => 'Notify');
Notify->init;
my $hello = Notify::Notification->new('Hello world!',
                                      'This is an example notification.',
                                      'dialog-information');
$hello->show;

Using direct D-Bus calls

hello_world.pl
#!/usr/bin/perl
use Net::DBus;
my $bus = Net::DBus->session;
my $svc = $bus->get_service('org.freedesktop.Notifications');
my $obj = $svc->get_object('/org/freedesktop/Notifications');
my $id = $obj->Notify('myapp', 0,
                      'dialog-information',
                      'Hello world!',
                      'This is an example notification.',
                      [], {}, 0);

Python

hello_world.py
#!/usr/bin/python
import gi
gi.require_version('Gio', '2.0')
from gi.repository import Gio
Application = Gio.Application.new("hello.world", Gio.ApplicationFlags.FLAGS_NONE)
Application.register()
Notification = Gio.Notification.new("Hello world")
Notification.set_body("This is an example notification.")
Icon = Gio.ThemedIcon.new("dialog-information")
Notification.set_icon(Icon)
Application.send_notification(None, Notification)
hello_world.py
#!/usr/bin/python
import gi
gi.require_version('Notify', '0.7')
from gi.repository import Notify
Notify.init("Hello world")
Hello = Notify.Notification.new("Hello world", "This is an example notification.", "dialog-information")
Hello.show()
hello_world.py
#!/usr/bin/env python
import dbus

notify_interface = dbus.Interface(
    object=dbus.SessionBus().get_object("org.freedesktop.Notifications", "/org/freedesktop/Notifications"),
    dbus_interface="org.freedesktop.Notifications")

notify_interface.Notify("", 0, "", "Hello world", "This is an example notification.", [], {"urgency": 1}, 10000)

For the arguments in the method Notify, please refer to the section of org.freedesktop.Notifications.Notify at Desktop Notifications Specification.

Ruby

hello_world.rb
#!/usr/bin/ruby
require 'gir_ffi'
GirFFI.setup :Notify
Notify.init("Hello world")
Hello = Notify::Notification.new("Hello world!", "This is an example notification.", "dialog-information")
Hello.show

Rust

Using notify-rust.

  • Makedependency: rust
  • Build with: cargo build
  • Run with: target/debug/hello_world or cargo run
Cargo.toml
[package]
name = "hello_world"
version = "0.1.0"

[dependencies]
notify-rust = "^3"
src/main.rs
extern crate notify_rust;
use notify_rust::Notification;
fn main(){
    Notification::new()
        .summary("Hello world")
        .body("This is an example notification.")
        .icon("dialog-information")
        .show().unwrap();
}

Scala

  • Dependency: java-gnomeAUR (and scala)
  • Makedependency: scala
  • Build with: scalac -cp /usr/share/java/gtk.jar -d HelloWorld.jar HelloWorld.scala
  • Run with: java -cp /usr/share/java/gtk.jar:HelloWorld.jar HelloWorld (or scala -cp /usr/share/java/gtk.jar HelloWorld.scala)
HelloWorld.scala
import org.gnome.gtk._
import org.gnome.notify._

object HelloWorld {
  def main(args: Array[String]) {
    Gtk.init(args)
    Notify.init("Hello world")
    var Hello = new Notification("Hello world!", "This is an example notification.", "dialog-information")
    Hello.show()
  }
}

Vala

  • Dependency: glib2
  • Makedependency: vala
  • Build with: valac --pkg gio-2.0 hello_world.vala
hello_world.vala
using GLib;
public class HelloWorld {
	static void main () {
		var Application = new GLib.Application ("hello.world", GLib.ApplicationFlags.FLAGS_NONE);
		Application.register ();
		var Notification = new GLib.Notification ("Hello world");
		Notification.set_body ("This is an example notification.");
		var Icon = new GLib.ThemedIcon ("dialog-information");
		Notification.set_icon (Icon);
		Application.send_notification (null, Notification);
	}
}
  • Dependency: libnotify
  • Makedependency: vala
  • Build with: valac --pkg libnotify hello_world.vala
hello_world.vala
using Notify;
public class HelloWorld {
	static void main () {
		Notify.init ("Hello world");
		var Hello = new Notify.Notification("Hello world!", "This is an example notification.", "dialog-information");
		Hello.show ();
	}
}

Visual Basic .NET

  • Dependency: notify-sharp-3
  • Makedependency: mono-basicAUR
  • Build with: vbnc -r:/usr/lib/mono/notify-sharp-3.0/notify-sharp.dll hello_world.vb
  • Run with: mono hello_world.exe
hello_world.vb
Imports Notifications
Public Class Hello
	Public Shared Sub Main
		Dim Hello As New Notification
		Hello.Summary  = "Hello world!"
		Hello.Body     = "This is an example notification."
		Hello.IconName = "dialog-information"
		Hello.Show
	End Sub
End Class

Tips and tricks

Replace previous notification

Notifications can be replaced if their ID is known; if a new notification request specifies the same ID, it will always replace the old notification. (The libnotify bindings shown above handle this automatically.) Unfortunately notify-send does not report this ID, so alternative tools are required to do this on CLI. One capable CLI-tool is the notify-send.py python script, which provides notify-send syntax with additional ID-reporting and replacing capabilities.

However, with some notification servers (such as Notify-OSD), you can use the string:x-canonical-private-synchronous: hint with notify-send to achieve the same result.

For example, to get a notification displaying time:

while true; do
  date=$(date)
  notify-send "$date" -h string:x-canonical-private-synchronous:my-notification
  sleep 1
done

Include Buttons or listen for close/on-click of the notification

With the notify-send.py script, actions can be used to display buttons or to listen for the default-action of the notification (usually, when the user clicks on it) and the close-action. When the action-icons hint is set to true and the notification daemon supports this, the buttons will display icons instead of text. The script prints the action identifier or "close" to the command line when the corresponding event has occured. To listen for the default action (on-click), one has to use the action-identfier "default".

Example with icons on buttons:

notify-send.py "Buttons" "Do you like em?" --hint boolean:action-icons:true --action yes:face-cool no:face-sick

Multiple notification servers with D-Bus services

As described in the section Standalone, users can create a D-Bus service so that a notification server can be launched automatically. Some implementations already include the D-Bus service files. However, this causes a problem when multiple notification servers are installed and when some of them come with the service files. For example, installing both dunst and mako without explicitly specifying the desired server, D-Bus then chooses one for the users, and the decision is out of users' control. To avoid the situation, it may be better to explicitly launch the desired server either manually, through autostart, or through systemd.

Troubleshooting

Applications hanging for exactly one minute

If applications hang when attempting to show notifications, it might be because of a notification service falsely advertising its availability through the D-Bus service.

For instance, suppose a user recently installed a KDE component that requires plasma-workspace, but the user is still running XFCE. In this case, the KDE notifier will be prioritized, but the user is not running it. The application will hang while waiting for the service, and only after a timeout will it fall back to xfce4-notifyd.

The most noticeable hanging might come from the volume indicator scroll adjustment.

If you are in this situation, you should have two notification handlers:

$ find /usr/share/dbus-1/services/ -name '*Notif*'
org.kde.plasma.Notifications.service
org.xfce.xfce4-notifyd.Notifications.service

Of those two, one fails regularly after a 1-minute timeout, as seen in the journal:

# journalctl -g notif
[ press End to go to the end of the log ]
Jul 01 09:40:49 laptop dbus-daemon[866]: [session uid=1000 pid=866] Activating service name='org.freedesktop.Notifications' requested by ':1.193' (uid=1000 pid=5432 comm="/usr/lib/xfce4/panel/wrapper-2.0 /usr/lib/xfce4/pa")
Jul 01 09:41:49 laptop plasma_waitforname[6093]: org.kde.knotifications: WaitForName: Service was not registered within timeout
Jul 01 09:41:49 laptop dbus-daemon[866]: [session uid=1000 pid=866] Activated service 'org.freedesktop.Notifications' failed: Process org.freedesktop.Notifications exited with status 1

A solution to this is to uninstall the failing one and reboot: [1]. In this example, the user might want to uninstall plasma-workspace.

See also