Hello,
Your site under maintenance mode, so I can’t check it.
Looks like XStore Core plugin is deactivated on your site or version of this plugin is not suitable to the theme version. Please check our changelog – https://xstore.8theme.com/update-history/ http://prntscr.com/poqc7m http://prntscr.com/poqcb2
https://www.8theme.com/documentation/xstore/theme-installation/theme-update/
https://www.8theme.com/documentation/xstore/plugins/plugins-update/
Here you can find a list of required plugins – https://www.8theme.com/documentation/xstore/plugins/included-plugins/
Regards