Warning: require_once [closed]

Answer 1

/home3/mathiasf/public_html/wp-admin/includes/class-wp-list-table.php doesn't exists.

It says so there in the log, No such file or directory

Answer 2

It means exactly what it says, '/home3/mathiasf/public_html/wp-admin/includes/class-wp-list-table.php' does not exist on your server.