The WordPress 5 Gutenberg update will probably hose millions of websites tomorrow seeing how most themes and plugins aren’t set up to work with the new editor. This is mainly because of the underline horrible culture at Automatic of pushing auto updates on its users without the ability to opt-out. This probably finally will bite them tomorrow, and I suppose they still won’t care or listen to their users. (whelp..)
Personally I dislike Gutenberg. I think there are at least a half dozen better options out there like (VisualBakery, Divi, PageBuilder, Composer, etc..) that are more advanced, supported, modern, and most of all – don’t break my current themes or plugins.
If you manage hundreds of websites and tomorrow some of your sites auto update and editing is totally broken, there is hope. Here are a few lines of code to add to your themes functions.php file in your theme directory so you can save your sanity while you waste your time and money trying to fix them.
Disable Gutenberg Completely WordPress 5.0: (add to: functions.php)
Disable Gutenberg Plugin Version in WordPress 4.9.8 (add to: wp-config.php)
$_GET['classic-editor'] = true;
There is also a plugin that will do the same thing that you can download here.