Hello,
Do update of the theme – https://www.8theme.com/documentation/xstore/theme-installation/theme-update/ first and after that update the Core plugin – https://www.8theme.com/documentation/xstore/plugins/plugins-update/
Did you make changes in the files of the theme? What exactly was broken? Could you provide screenshots? What version of the theme do you use right now? Do you need help with the update?
Regards