How to get the content into sidebar back after theme migration.

If your old theme had some custom areas in Appearance > Widgets, you may lose them when switching to the Jupiter X theme. The reason is that Jupiter X is designed differently and has its own widget areas.
To get the content in your sidebars back, you’ll need to add the widgets again to the new Widget Areas.

Note: To learn more about adding widgets to widget areas, check out this article.