The max_input_vars limitation error is a very common issue that most WordPress web developers and website owners may encounter at some point in their career. Few days ago, my website also experienced the same problem. The solution is very simple; increase the value assigned to max_input_vars in the PHP configuration file on the web server. However, depending on server setup, you may have to do few more things to get this problem fixed.
Editing php.ini may result in complete failure of the php module and it may put your website out of service. If you are hesitant about something, hire a professional. I take no responsibility for any issues arise out of the following instructions.