Quote Originally Posted by linuxguy2 View Post
Upps...More issues:

When on the checkout page clicking the "Save Changes" button under any circumstances generates one of these errors for every entry in the address form.

Code:
[03-Mar-2019 03:53:05 UTC] PHP Notice:  Undefined index: countries_iso_code_2 in /home/pcsnnets/public_html/156a/includes/classes/order.php on line 451
[03-Mar-2019 03:53:05 UTC] PHP Notice:  Undefined index: countries_iso_code_3 in /home/pcsnnets/public_html/156a/includes/classes/order.php on line 451
[03-Mar-2019 03:53:05 UTC] PHP Notice:  Undefined index: entry_country_id in /home/pcsnnets/public_html/156a/includes/classes/order.php on line 452
[03-Mar-2019 03:53:05 UTC] PHP Notice:  Undefined index: address_format_id in /home/pcsnnets/public_html/156a/includes/classes/order.php on line 453
Phew, that one took a bit of investigation! Corrected via this (https://github.com/lat9/one_page_checkout/issues/169) GitHub issue.

The problem was that when neither Guest Checkout nor Registered Accounts were enabled, the plugin's observer no longer monitored the address-related notifications. When a customer changed their address to a temporary one, the temporary address was not being filled into the order's billing and/or shipping blocks.