Don’t update WordPress 5.0 blindly if you are using divi, simply first go to update the divi first at least divi version 3.18 and then go to update the WordPress
Basically divi have a compatibility issue with Gutenberg but happily divi and elegant theme already solve this issue
Divi after update in wordpress 5.0
After download and install this new Divi Version your divi will fully compatible with new WordPress 5.0 Gutenberg