Notification service is not running on openSUSE Tumbleweed

[Klaus Zeitler]

Hello,
just installed openSUSE Tumbleweed for the first time. I'm using
gdm as display manager and, as usual, xfce as window manager.
Unfortunately notification service is down.
According to /usr/lib/systemd/user/xfce4-notifyd.service
the session manager is trying to run /usr/lib/xfce4/notifyd/xfce4-notifyd.
But this fails with:
Activated service 'org.freedesktop.Notifications' failed

With journalctl I found 12 lines matching the string "notif":
--- snip ---
Oct 18 17:55:15 stenopus cron[2071]: (CRON) INFO (running with inotify support)
Oct 18 17:55:57 stenopus dbus-daemon[2313]: [session uid=1000 pid=2313]
Activating service name='org.freedesktop.Notifications' requested by ':1.31'
(uid=1000 pid=2564 comm="xfce4-power-manager ")
Oct 18 17:56:02 stenopus panel-14-notifi[2634]: g_file_new_for_path: assertion
'path != NULL' failed
Oct 18 17:56:02 stenopus panel-14-notifi[2634]: g_file_monitor_file: assertion
'G_IS_FILE (file)' failed
Oct 18 17:56:02 stenopus panel-14-notifi[2634]: invalid (NULL) pointer instance
Oct 18 17:56:02 stenopus panel-14-notifi[2634]: g_signal_connect_data:
assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
Oct 18 17:56:02 stenopus panel-14-notifi[2634]: Attempting to add a widget
with type GtkToggleButton to a container of type XfcePanelPlugin, but the
widget is already inside a container of type XfcePanelPlugin, please remove
the widget from its existing container first.
Oct 18 17:56:03 stenopus panel-14-notifi[2634]: Negative content width -17
(allocation 1, extents 9x9) while allocating gadget (node button, owner
GtkToggleButton)
Oct 18 17:56:12 stenopus xfce4-notifyd-c[2723]: GtkDialog mapped without a
transient parent. This is discouraged.
Oct 18 17:56:33 stenopus xfce4-notifyd-c[2738]: GtkDialog mapped without a
transient parent. This is discouraged.
Oct 18 17:56:59 stenopus plasma_waitforname[2581]: org.kde.knotifications:
WaitForName: Service was not registered within timeout
Oct 18 17:56:59 stenopus dbus-daemon[2313]: [session uid=1000 pid=2313]
Activated service 'org.freedesktop.Notifications' failed: Process
org.freedesktop.Notifications exited with status 1
--- snip ---

I don't have any clue what the error is, that is causing the service to fail.
Is it one of the "xfce4-notifyd-c" errors above or could it be one of these
"panel-14" messages?
Oddly enough I can start the notification service manually just fine with:
systemctl --user start xfce4-notifyd

I hope somebody can help me here.

Thanks

Klaus

-- 
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|  Klaus Zeitler                |
|  Email: info at klauszeitler.de  |
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---
There's only one way to have a happy marriage and as soon as
I learn what it is I'll get married again. -- Clint Eastwood