php wordpress composer-php wordpress-plugin-creation

call_user_func_array(): Argument #1 ($callback) must be a valid callback

I'm currently developing a WordPress plugin. The main class I have created activates and deactivates all necessary functions, settings and files for the plugin and I use composer to manage the inclusion of classes.

Yesterday I changed the main psr-4 folder from src/ to admin/builder/ and this caused problems.
Now the hierarchy of the project is like this:

onfeed-facebook\
|---admin\
    |---builder
        |---Action\
        |---RSA\
        |---View\
        |---OnFeedMain.php
|---vendor\
|---assets\
|---onfeed.php
|---...

I should point out that after editing the composer.json file I also ran the composer dump-autoload command... but I still get this error:

Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, first array member is not a valid class name or object in C:\www\clientwp.local\wp-includes\class-wp-hook.php:310 
Stack trace: 
#0 C:\www\clientwp.local\wp-includes\class-wp-hook.php(334): WP_Hook->apply_filters('', Array) 
#1 C:\www\clientwp.local\wp-includes\plugin.php(517): WP_Hook->do_action(Array) 
#2 C:\www\clientwp.local\wp-admin\includes\plugin.php(816): do_action('deactivate_onfe...', false) 
#3 C:\www\clientwp.local\wp-admin\plugins.php(209): deactivate_plugins('onfeed-facebook...', false, false) 
#4 {main} thrown in C:\www\clientwp.local\wp-includes\class-wp-hook.php on line 310

Here's the composer.json file:

    "autoload": {
        "psr-4": {
            "Oppimittinetworking\\OnfeedFacebook\\": "admin/builder/"
        }
    },
    "config": {
        "optimize-autoloader": true
    }

This is the OnFeedMain.php Class:

namespace Oppimittinetworking\OnfeedFacebook;
use Oppimittinetworking\OnfeedFacebook\Action\ONFActivate;
use Oppimittinetworking\OnfeedFacebook\Action\ONFDeactivate;
use Oppimittinetworking\OnfeedFacebook\RSA\ONFRSAEncrypt;
use Oppimittinetworking\OnfeedFacebook\RSA\ONFRSADecrypt;

class OnFeedMain {

    public function __construct() {
        ONFActivate::activate();
        ONFActivate::register_admin_scripts();
        ONFActivate::register_wp_scripts();
    }

    public function __deactivate() {
        ONFDeactivate::deactivate();
        ONFDeactivate::unregister_admin_scripts();
        ONFDeactivate::unregister_wp_scripts();
    }

    public static function encrypt_conn() { return new ONFRSAEncrypt(); }
    public function decrypt_data() { return new ONFRSADecrypt(); }
}

Here's the onfeed.php file:

require_once ONFEED_PLUGIN_PATH . '/vendor/autoload.php';
use Oppimittinetworking\OnfeedFacebook\OnFeedMain;

if ( class_exists( 'OnFeedMain' ) )
    $onfmain = new OnFeedMain();

// activaion hook
register_activation_hook( __FILE__, array( $onfmain, '__construct' ) );

// deactivation hook
register_deactivation_hook( __FILE__, array( $onfmain, '__deactivate' ) );

Here's the functions inside ONFActivate.php and ONFDeactivate.php classes:
ONFActivate.php:

namespace Oppimittinetworking\OnfeedFacebook\Action;

class ONFActivate {

    public static function activate() {
        // No relevant code ...
    }

    public static function register_admin_scripts() {
        add_action( 'admin_enqueue_scripts', array( 'Oppimittinetworking\OnfeedFacebook\Action\ONFActivate', "enqueue_admin" ) );

        add_action( 'admin_menu', array( "Oppimittinetworking\OnfeedFacebook\Action\ONFActivate", 'add_admin_pages' ) );
    }

    public static function add_admin_pages() {
        add_menu_page( 'OnFeed Facebook', 'OnFeed Facebook', 'manage_options', 'onfeed_admin_menu', array( 'Oppimittinetworking\OnfeedFacebook\Action\ONFActivate', 'admin_index' ), 'dashicons-facebook-alt', 110 );
    }

    public static function admin_index() {
        require_once plugin_dir_path( __FILE__ ) . '../../admin/builder/index.php';
    }

    public static function register_wp_scripts() {
        // TODO
    }

    public static function enqueue_admin() {
        // Enqueue admin css files
        // Bootstrap@5.3.0
        wp_register_style( "bootstrap", "https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" );
        wp_enqueue_style( "bootstrap" );

        // FontAwesome@6.4.0
        wp_register_style( "font_awesome", "https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css" );
        wp_enqueue_style( "font_awesome" );

        wp_enqueue_style( "onfeed_main_css", plugins_url( "../../assets/css/main.css", __FILE__ ) );
        wp_enqueue_style( "onfeed_shortcut_css", plugins_url( "../../assets/css/shortcut.css", __FILE__ ) );
        wp_enqueue_style( "onfeed_feedspage_css", plugins_url( "../../assets/css/feedspage.css", __FILE__ ) );
        
        // Enqueue admin js files
        // jQuery@3.6.3
        wp_enqueue_script( "jquery_3_7_1-min", plugins_url( "../../assets/js/jquery-3.7.1.min.js", __FILE__ ), null, '3.7.1', array( 'strategy' => 'async' ) );

        wp_enqueue_script( "onfeed_function_js", plugins_url( "../../assets/js/function.js", __FILE__ ), null, '2.2.0', array( 'strategy' => 'defer' ) );
        wp_enqueue_script( "onfeed_handshake_js", plugins_url( "../../assets/js/handshake.js", __FILE__ ), null, '2.2.0', array( 'strategy' => 'defer' ) );
        wp_enqueue_script( "onfeed_shortcut_js", plugins_url( "../../assets/js/shortcut.js", __FILE__ ), null, '2.2.0', array( 'strategy' => 'defer' ) );
        wp_enqueue_script( "onfeed_feedspage_js", plugins_url( "../../assets/js/feedspage.js", __FILE__ ), null, '2.2.0', array( 'strategy' => 'defer' ) );
    }

    public static function enqueue_wp() {
        // TODO
    }
}

ONFDeactivate.php:

namespace Oppimittinetworking\OnfeedFacebook\Action;

class ONFDeactivate {

    public static function deactivate() {
        // Not relevant code ...
    }

    public static function unregister_admin_scripts() {
        add_action( 'admin_dequeue_scripts', array( 'Oppimittinetworking\OnfeedFacebook\Action\ONFDeactivate', "dequeue_admin" ) );
    }

    public static function unregister_wp_scripts() {
        // TODO
    }

    public static function dequeue_admin() {
        // Enqueue admin css files
        wp_dequeue_style( "onfeed_main_css" );
        wp_dequeue_style( "onfeed_shortcut_css" );
        wp_dequeue_style( "onfeed_feedspage_css" );

        // Enqueue admin js files
        wp_dequeue_script( "onfeed_main_js" );
        wp_dequeue_script( "onfeed_shortcut_js" );
        wp_dequeue_script( "onfeed_feedspage_js" );
    }

    public static function dequeue_wp() {
        // TODO
    }
}

I would also let you all know thta I've checked if the problem was caused by the uncorrect namespace, but how you can see there's no problem with that.

I've also checked this link:

Uncaught TypeError: call_user_func_array(): Argument #1 ($function) must be a valid callback

but the problem still.

Thanks in advance for your reply.

Solution

I've resolved the issue by updating this line: If ( class_exists( 'OnFeedMain' ) ) inside onfeed.php.
I've forgot to insert the correct namespace:

If ( class_exists( 'OnFeedMain' ) )
    $onfmain = new OnFeedMain();

To:

If ( class_exists( 'Oppimittinetworking\OnfeedFacebook\OnFeedMain') )
    $onfmain = new OnFeedMain();