How to migrate old content to Jupiter X
Jupiter X uses Elementor as it’s main page builder, so most likely you will have to recreate the pages from scratch. Unfortunately to convert the page from your old content to the Elementor is impossible, it has to be done manually by recreating the whole page.
To learn how to properly upgrade to Jupiter X, check out this article.
Note: But don’t worry, you can still use the WPBakery Page Builder to maintain your website, but it is highly recommended to convert everything to Elementor because of it’s features and performance.