There’s nothing wrong with 5.6.
Chances are YOUR theme or some plugin you have installed using is not compatible with 5.6, causing your site to break.
There are simple steps to take find out which 3rd-party to you have installed is incompatible and causing the site to break, and what solutions there may be. But that begins with having the right attitude!
You can use the “Troubleshooting” tab of the “Health Check & Troubleshooting” plugin isolate the source of your problem: https://wordpress.org/plugins/health-check/
Is it possible to downgrade
You can always downgrade to any previous version of WordPress. There’s no “Downgrade” button though: you have to manually upload whatever version you want to return to. See all previous releases here: https://wordpress.org/download/releases/
Good luck!
George, i’ve been using WP for 7 years and never saw something like this.
The story of the broken plugin or theme is very nice to tell, the story of why they stop to update the jQuery library in 2016…not so much.
I, personally, have everything updated as soon it comes out (WP 5.6 seems like a good example), and besides that, if i have some plugin, it’s not because i like the name of it or the icon, but because i need it.
Thank you for the link.