when clicking add product or edit product, turn up errro 500

-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.6.2
-- PHP version -- : 7.2.3
-- Error-message(debug-mod must be tuned on) -- : Fatal error: Declaration of JToolbarButtonHikapopup::fetchButton($type = 'Modal', $name = '', $text = '', $url = '', $width = 640, $height = 480, $top = 0, $left = 0, $onClose = '', $title = '') must be compatible with JToolbarButtonPopup::fetchButton($type = 'Modal', $name = '', $text = '', $url = '', $width = 640, $height = 480, $top = 0, $left = 0, $onClose = '', $title = '', $footer = NULL) in /home/aonepart/public_html/administrator/components/com_hikashop/buttons/hikapopup.php on line 45

hello

I backup my site on server A and restore it on server B.

in server A the add product and edit product function are fine but in server B when clicking add product or edit product then the page turn up error 500...and the error message shows on the page as above.

I do not know what causes this situation...

please help me to solve it.

thank you very much.