[Gelöst] Help me fix the error

Background of the issue:
I was trying to switch languages on my site, and I encountered a problem. The issue can be seen on this page: versteckter Link

Symptoms:
When I switched languages, my site got a fatal error. Additionally, some images are not displayed, and text is not translated.The webpage displays a fatal error

Questions:
How can I fix the fatal error when switching languages?
How can I configure translations to ensure images and text are displayed correctly?