What version of our theme do you use? Min required version of XStore theme for the core plugin 1.2.7 is 5.6. If previous plugin version is 1.0.23 then you use out of date version 4.x or earlier and of course, you’ll get the fatal error if you are trying to update just XStore core plugin. Provide Dashboard access to your site and correct FTP access if you need help with theme and plugin update.
