php post with big array

Starting from php 5.3.9 there is brand new config option max_input_vars which is limiting the input variables to posted arrays and etc.

max_input_vars integer

How many input variables may be accepted (limit is applied to $_GET, $_POST and $_COOKIE superglobal separately). Use of this directive mitigates the possibility of denial of service attacks which use hash collisions. If there are more input variables than specified by this directive, an E_WARNING is issued, and further input variables are truncated from the request. This limit applies only to each nesting level of a multi-dimensional input array.

Default value is 1000, to set different value you need to add to your php.ini

max_input_vars = 3000