Hi,
Add the code:
if(!class_exists($classType)){
return 'Plugin '.$field_type.' missing or deactivated';
}
after the line:
$classType = 'hikashop'.ucfirst($field_type);
(several places) in the file /administrator/components/com_hikashop/classes/field.php and that should avoid the problem.
You'll have to deactivate the date picker field that you have via the menu Display>Custom fields or enable the plugin for it via the Joomla plugins manager.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.