I'm teaching myself from a plugin tutorial dvd, everything was going fine. I've setup custom_post_types and the metaboxes with no issues. The issue i have is a fatal error when i update/publish the post

Fatal error: Uncaught ArgumentCountError: Too few arguments to function mdb_save_metaboxes(), 1 passed in C:\xampp\htdocs\wordpress\wp-includes\class-wp-hook.php on line 310 and exactly 3 expected in C:\xampp\htdocs\wordpress\wp-content\plugins\maxi_metaboxes\maxi_metabox_types.php:45 Stack trace: #0

To check i was not adapting the code incorrectly, I back tracked and used the tutors metaboxes and code that worked for him, but it still doesn't.

I have a good idea it is to do with the verify_nonce check in the mdb_save_metaboxes function. Any help will be greatly accepted.


 * Plugin Name:      Driver Bible metaboxes
 * Plugin URI:        
 * Description:      Adds metaboxes to Driver Bible
 * Version:           1.0
 * Author:            Fuzzy
 * Author URI:        
 * License:           GPL v2 or later
 * License URI:       https://www.gnu.org/licenses/gpl-2.0.html

  function mdb_add_metaboxes() {
    add_meta_box('mdb-metaboxes', 'Dealer Info', 'mdb_metaboxes_container', 'dealers', 'normal', 'high', 'null');
add_action('add_meta_boxes', 'mdb_add_metaboxes');

//Add metaboxes
function mdb_metaboxes_container($post) {

    wp_nonce_field(basename(__FILE__), "meta-box-nonce");
        <label for="input-metaboxes">Cal:</label>
        <input type="text" name="input-metabox" value="<?php echo get_post_meta($post->ID, "input-metabox", true); ?>">
        <label for="textarea-metaboxes">text area:</label>
        <textarea type="text" name="textarea-metabox"><?php echo get_post_meta($post->ID, "textarea-metabox", true); ?></textarea>


//Saving metabox updates

//permissions check
add_action('save_post', 'mdb_save_metaboxes');
function mdb_save_metaboxes($post_id, $post, $update){
    if (!isset($_POST["meta-box-nonce"]) || !wp_verify_nonce($_POST["meta-box-nonce"], basename(__FILE__)))
        return $post_id;

    if(!current_user_can("edit_post", $post_id))
        return $post_id;

        return $post_id;

// save

$input_metabox ='';
$textarea_metabox ='';

if(isset($_POST["input-metabox"])) {
    $input_metabox = $_POST["input-metabox"];
update_post_meta($post_id, "input-metabox", $input_metabox );

if(isset($_POST["textarea-metabox"])) {
    $textarea_metabox = $_POST["textarea-metabox"];
update_post_meta($post_id, "textarea-metabox", $textarea_metabox );


1 Answer 1


You are getting that fatal error because your custom mdb_save_metaboxes function is expecting to receive 3 parameters (function mdb_save_metaboxes($post_id, $post, $update)), but WordPress only passed 1 parameter, because you did not tell WordPress that it needs to pass 3 parameters.

So to fix the issue, set the fourth parameter for add_action() like so:

// If you do this, only 1 parameter will be passed to mdb_save_metaboxes:
add_action('save_post', 'mdb_save_metaboxes');

// So do this instead, to ensure that 3 parameters passed to the function.
add_action('save_post', 'mdb_save_metaboxes', 10, 3);
  • That makes total sense.Thank you so much Sally works well now, just got to put all my boxes back in :-}
    – fuzzy2023
    Mar 29, 2023 at 14:22
  • Glad it helped! But just a friendly note, remember to sanitize and validate the inputs, and remember also, that if you want to group similar things together, taxonomy is the proper approach for that (e.g. a category named comedy, as opposed to a custom field or meta named comedy, for posts about comedy) :)
    – Sally CJ
    Mar 29, 2023 at 16:30

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