Fatal error: Call to undefined function wp_create_nonce()

I’m trying to add a nonce to my plugin’s Ajax. I’m not sure why I’m getting this error:

Fatal error: Call to undefined function wp_create_nonce()

In my php file :

wp_localize_script('my-ajax-handle', 'the_ajax_script', array('ajaxurl'=> admin_url('admin-ajax.php'), 'my_nonce' => wp_create_nonce('myajax-nonce')));

In js file:

jQuery.post(the_ajax_script.ajaxurl, {my_nonce : the_ajax_script.my_nonce}, jQuery("#theForm").serialize() + "&maxLat="+ map_bounds[0] + "&maxLong="+ map_bounds[1] + "&minLat="+ map_bounds[2] + "&minLong="+ map_bounds[3],
    function(response_from_the_action_function){
       jQuery("#response_area").html(response_from_the_action_function);
    });

Any suggestions on how to solve this?

Thank you.

More context would be helpful. Is that all the code found in your plugin or functions file directly? Or are you hooking in to something via add_action.

Anyway, what’s probably wrong is that you’re calling wp_localize_script and wp_enqueue_script outside of an action. wp_create_nonce, or, rather, the file in which it resides, has yet to be loaded.

The solution is to call wp_localize_script from inside a function hooked into wp_enqueue_scripts

<?php
add_action( 'wp_enqueue_scripts', 'wpse30583_enqueue' );
function wpse30583_enqueue()
{
    // your enqueue will probably look different.
    wp_enqueue_script( 'wpse30583_script' );

    // Localize the script
    $data = array( 
        'ajax_url' => admin_url( 'admin-ajax.php' ),
        'nonce'    => wp_create_nonce( 'wpse30583_nonce' )
    );
    wp_localize_script( 'wpse30583_script', 'wpse3058_object', $data );
}