Increasing Max Input Vars in .htaccess File
It’s possible to increase it from .htaccess file in root WordPress installation’s directory. For this you need connect to your server via FTP (using some FTP client like FileZilla), find .htaccess file in the root of your site directory (or create it yourself if it’s missing) and add below lines of codes at the end of the .htaccess file:
php_value max_input_vars 3000 php_value suhosin.get.max_vars 3000 php_value suhosin.post.max_vars 3000 php_value suhosin.request.max_vars 3000
Increasing Max Input Vars in php.ini File
For this scenario you should also connect via FTP or log in to the CPanel of your hosting provider.
At the end of the php.ini file, add below lines of codes. The php.ini file can be found in /user/local/bin/, /etc/php5/ or … depending on the host provider. If you can not find it, it’s better contact your hosting provider. On some hosting providers, you can create a php.ini file in the root directory and just add the following codes to override the default values.
max_input_vars = 3000 suhosin.get.max_vars = 3000 suhosin.post.max_vars = 3000 suhosin.request.max_vars = 3000