Non visible icons after upgrade nc14 to nc15

after updating from nc14.0.10 to nc15.0.8 I have a problem that there are no visible parts of the icons in the web interface. It looks like the button link itself is and you can click it, but the icon is not displayed.
the same is true for the image preview, the links are (because I know where they should also be clicked), but there is no visual presentation.
What to check, or what to do to determine the cause?

Hey waldekfras

Welcome to the community!

As for your problem, there is a repair command you can run but this requires SSH access or the WebOCC app for Nextcloud.

Here is a link to the documentation of Nextcloud, regarding the OCC command.

There you will find the maintenance:repair command. Try this one first and see if the icons are being shown afterwards.

After running the sudo -u command www-data ./occ maintenance: repair has become a standard message. Unfortunately, nothing has changed and I still have no icons. Can I still do something? In which folder the icons are pushed, I can just check if they are on the server;)
PS. I wonder if the update to nc16 will change, I will try today or tomorrow night.

After a few minutes and a certain amount of reloads (maybe there was something still in the cache) everything is fine again.
Thank you for your help, greetings.