The PHP variable “max_input_vars” was introduced in PHP 5.3.9+ as a security measure to limit the maximum amount of POST variables submitted, by default this limit is set to 1000.
In the Apache error log you will see an error like this:
"PHP Warning: Unknown: Input variables exceeded 1000. To increase the limit change max_input_vars in php.ini."
To resolve, the default value can be increased as per below.
Note: This was completely fixed in WordPress 4.5 and above. If you’re not running the latest version of WordPress, we highly recommend upgrading instead of making the changes below.
Create or update your .htaccess file and add the following line:
php_value max_input_vars 3000
Note: Your hosting provider may not allow this to be overridden, if this doesn’t work then please check with your provider.
- Log into Plesk.
- Click on PHP Settings:
- At the bottom of the page in Additional configuration directives field add “max_input_vars” parameter with recommended value or greater:
max_input_vars = 3000
Note: The field “Additional configuration directives” in Plesk is only available to the Plesk Panel Administrator