alrmoras on "Date Permalinks error - Fatal error: Class 'WP_Date_Query' not found."

Hi everybody.

I've setup my website and set my permalinks to use /%year%/%monthnum%/%day%/%post_id% but when I try and visit the post, I get the following error;
Fatal error: Class 'WP_Date_Query' not found in /home/a5462226/public_html/wp-includes/query.php on line 2303
I've tried manually reinstalling wordpress, changing themes and deactivating/reactivating all plugins and nothing seems to fix it. My error logs don't show any errors, the only thing I do know is that if I change my permalinks, it doesn't work with the dates.

Your help is much appreciated.