[Решено] I cant edit the homepage in Dutch anymore

Background of the issue:
I am trying to edit the homepage on my site скрытая ссылка using WordPress. I am using WPML for multilingual support.

Symptoms:
I get a 500 error when I try to edit the homepage in Dutch.

Questions:
Why am I getting a 500 error when trying to edit the homepage in Dutch?
How can I resolve the 500 error to edit the homepage?