You spend minutes maybe even an hour creating a menu that has one, two maybe even three levels- click submit and only half of your menu saved! Below is the solution but checkout the below page for more information:
PHP’s max_input_vars
max_input_vars manages the how many input variables may be accepted (limit is applied to $_GET, $_POST and $_COOKIE superglobal separately). By default it is set to 1000. Edit your php.ini file and update the number to 3000 or even 4000.