Wolfgang Mueller wrote:

After I upgraded to Leap 15.2, boring error messages appear showing the following content:

Software updates       1 min ago Update error Failed to obtain authentication.

See also http://ariannuccia.de/temp/update_error.k76.jpg

Is there any way to provide the missing authentication? If not so, how can I suppress the messages?

Right click on the icon, then "Configure Event Notifications and Actions ..."