it’s done, although I tried for hours before, it now suddenly takes the entries…
Problem can be closed, but I don’t know the solution.
Oh, of course I tried safe mode, standard theme and also deactivated all plugins (except for the calendar) but still the error occurs.
I have all plugins and also WordPress on the latest version, PHP 8.3 (but the error is also with PHP 7.4 and PHP 8.1, 8.2)