Cannot add or edit user addresses (pop-up is blank)

-- HikaShop version -- : 3.1.0
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.1.5
-- Browser(s) name and version -- : Chrome 58.0.3029.110 (64-bit)
-- Error-message(debug-mod must be tuned on) -- : Warning: Illegal string offset 'state_Alabama_4261' in /mnt/data/vhosts/casite-620018.cloudaccess.net/httpdocs/administrator/components/com_hikashop/classes/field.php on line 648

Recoverable fatal error: Object of class stdClass could not be converted to string in /mnt/data/vhosts/casite-620018.cloudaccess.net/httpdocs/administrator/components/com_hikashop/classes/field.php on line 648

Hello,

When I try to add or edit addresses in the User or Order screens, I'm not able to do so because the pop-up appears blank (in the user editor), or the section merely collapses (in the orders editor). You can see both in my screenshots.

I've pasted in the errors reported by Joomla with the maximum error reporting turned on.

What must I do to fix this? Thanks.

hI Jerome,

line 648 in the field php file is:

$fields[$k]->field_value[$zone->zone_namekey]=$obj;

* @package	HikaShop for Joomla!
 * @version	2.6.3