The only solution is to update the whole site including the theme, wordpress and plugins.
First update the Wordpress to the latest version which currently is WP 5.0.3
Then, you will have to update to Jupiter 6.1.6 which you can find in the THemeForest. You will have to download the whole bundle/package and inside you will find the files for both Jupiter 6 and Jupiter X.
Or you can also find the 6.1.6 files from here https://themes.artbees.net/dashboard/releases/
After that, deactivate & delete the plugins that ship with the theme. The go to Jupiter -> Control Panel -> Required Plugins and activate them from here. This will activate the latest version of the plugins that are compatible with the theme versions.