According to the producer of the plugin “Backup Pro”, there is an error in the theme, he writes on Email:
So I have found out why your website crashed. The issue is with the theme you are using. It broke the site when updating itself.
I found other users of the same theme facing the same issue too. So you can ask the theme developers why this issue would have happened. As the update of the theme will surely work.
hope you can find a solution to this problem by updating the theme