Website offline due to Gridbox?

Hi huys. I have a problem with my twi Joomla/Gridbox Websites:
https://www.wattnurlaub.de/
https://www.fahrrad-winkelmann.de/
Both show "Call to undefined method Joomla\CMS\Factory::getContainer()"
I cannot login to the backends, I only get an error.
Any Ideas. Those are customer websites so it is rather urgent!
Kind regards
Silke

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