If you have a blank WooCommerce Subscriptions or WooCommerce Checkout settings page after upgrading to WordPress 4.4 while running WooCommerce Subscriptions, then you might have run into an error caused by a modification in a core file that was released with WordPress version 4.4. This issue also prevents anyone from adding subscription products to the cart.
Turning on WP-DEBUG will get you this kind of error:
Fatal error: Uncaught exception 'Exception' with message 'SSL certificate problem: unable to get local issuer certificate'
The error has been fixed already and will be released in WordPress version 4.4.1. Until then as a workaround solution you can either:
- rollback to WP 4.3.1
- or try place the uploaded file inside directory
/wp-includes/certificates/and replace the existing file.
**Also: Before you do that, please do make a full backup!**