Some our clients faced with error in Theme Options after theme update.
If after saving Theme Options you got error 404 for wp-admin/options.php (see it in your console or redirects to 404 page).
We can recommend you to reinstall WordPress. Usually it solve error and you can work on the site.
If reinstalling didn’t help, please, check your server configurations. Low server configurations also can provoke error.
To check server configurations go to Theme Options > System check > click on Start testing button. After testing you’ll see recommendations in red.
This error almost always comes down to an .htaccess issue.Please check with your host (or if using a local install, make sure it’s activated) the apache mod_rewrite module.
Note, that this settings should be set on server, but not in the .htaccess site.
Also, check your site with your host with FireWall Web Application and the mode security, which can be blocking the WordPress files.
If you tried all solutions mentioned in this article and nothing helped, please, mail us to firstname.lastname@example.org, our support team will do our best to help you.
Regards, DFD Support Team