When your WordPress installation shows a critical error, then the issue is always with your plugins or theme. Sometimes this error goes away if you refresh the page, but sometimes it doesn't. In that case, you must enable WP_DEBUG to see what's wrong.
Sometimes you may be unable to log in to wp-admin to update your plugin(s) then you have to disable the conflicting plugin.
To do that, go to cPanel > File Manager, find your domain from the public_html folder and go to wp-content > plugins, and just rename your plugin's folder that's causing trouble. Then visit your website again and see if there are any more errors. Most of the time, your website's errors are gone, and you can log in to wp-admin, and the critical error is gone.