cannot update to WP 5.4

I cannot update to WP 5.4, I get this message when I try to:

Kan bestand niet kopi?ren: wordpress/wp-includes/js/tinymce/tinymce.min.js

I have tried to deactivate all plugins to see if that helped, but that didn’t do the trick.

The page I need help with: [log in to see the link]