I'm getting the following error...

Notice: Undefined index: album_tracks_metabox_nonce in /Applications/MAMP/htdocs/TheToasters/wp-content/themes/Toasters/discography-post-type.php on line 124

...whenever I attempt to add a new Page, Post or custom post type entry. If I'm editing an existing entry, all works fine.

Error screenshot

The error appears to be relating to a nonce for a metabox on the "Discography" custom post type I've created, here's the relevant code:

function album_tracks_content( $post ) {
    wp_nonce_field( 'album_tracks_metabox', 'album_tracks_metabox_nonce' );
    $albumTracks = get_post_meta( get_the_ID(), 'album_tracks', true);?>
    <p>1. <input type="text" id="track1" name="track1" placeholder="Track name" value="<?php echo isset($albumTracks[0]) ? $albumTracks[0] : ''; ?>"></p>
    <p>2. <input type="text" id="track2" name="track2" placeholder="Track name" value="<?php echo isset($albumTracks[1]) ? $albumTracks[1] : ''; ?>"></p>
<?php }
// Save Tracks metabox
function album_tracks_save( $post_id ) {
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) 

    if ( !wp_verify_nonce( $_POST['album_tracks_metabox_nonce'], 'album_tracks_metabox' ) )

    if ( 'page' == $_POST['post_type'] ) {
        if ( !current_user_can( 'edit_page', $post_id ) )
    } else {
        if ( !current_user_can( 'edit_post', $post_id ) )

    $albumTracks = array();
    if (isset($_POST['track1'])):
        $albumTracks[] = $_POST['track1'];
    if (isset($_POST['track2'])):
        $albumTracks[] = $_POST['track2'];
    if (!empty($albumTracks)):
        update_post_meta( $post_id, 'album_tracks', $albumTracks );
add_action( 'save_post', 'album_tracks_save' );


The exact line 124 is this:

if ( !wp_verify_nonce( $_POST['album_tracks_metabox_nonce'], 'album_tracks_metabox' ) )


Whoever wrote your theme didn't bother to verify the existence of array keys before using them. The error is happening because the key album_tracks_metabox_nonce doesn't exist in the $_POST array.

The line likely should be:

if (
  !isset($_POST['album_tracks_metabox_nonce']) ||
  !wp_verify_nonce($_POST['album_tracks_metabox_nonce'], 'album_tracks_metabox')
) {
  // whatever is in the if condition, likely `return`
  • That would be me, however this is not a theme for production/sale, just getting to grips with the Wordpress system (creating post types, taxonomys, metaboxes, and a long etc.). The code used was based on what I'd seen at codex.wordpress.org/Function_Reference/add_meta_box in the examples. Where they used if ( ! wp_verify_nonce($_POST['myplugin_meta_box_nonce'], 'myplugin_meta_box' ) ) { return; }. Non the less, your solution seems to have fixed the error - cheers! – Brad Adams Jan 11 '15 at 20:25
  • Arg, yes, right above the code I took is if ( ! isset( $_POST['myplugin_meta_box_nonce'] ) ) { return;} (basically what you've added... my bad) – Brad Adams Jan 11 '15 at 20:34

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