problem when uploading file by metaboxes

Question

I want to upload pdf files via posts using metaboxes. I have this code:

if ( is_admin() ) {
    add_action( 'load-post.php',     'call_MetaBoxClass' );
    add_action( 'load-post-new.php', 'call_MetaBoxClass' );
}

function call_MetaBoxClass() {
    new MetaBoxClass();
}


class MetaBoxClass {

    private $post_types = array( 'post', 'page' );

    public function __construct() {
        add_action( 'add_meta_boxes', array( $this, 'add_metaa_box' ) );
        add_action( 'save_post',      array( $this, 'save'         ) );
    }

    public function add_metaa_box( $post_type ) {
        add_action('post_edit_form_tag', 'update_edit_form');

        if ( in_array( $post_type, $this->post_types ) ) {
            add_meta_box(
                'MetaBoxId',
                __( 'MetaBox', 'textdomain' ),
                array( $this, 'render_meta_box_content' ),
                $post_type,
                'side'
            );
        }
    }


    public function save( $post_id) {

        $nonce = @$_POST['MetaBoxNonce_name'];


        if ( ! wp_verify_nonce( $nonce, 'MetaBoxNonce_action' ) ) {
            return $post_id;
        }

        if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
            return $post_id;
        }

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

        //----------------------------------


        if(!empty($_FILES['eventEsbat']['name'])) {


            $supported_types = array('application/pdf');


            $arr_file_type = wp_check_filetype(basename($_FILES['eventEsbat']['name']));
            $uploaded_type = $arr_file_type['type'];


            if(in_array($uploaded_type, $supported_types)) {


                $upload = wp_upload_bits($_FILES['eventEsbat']['name'], null, file_get_contents($_FILES['eventEsbat']['tmp_name']));

                if(isset($upload['error']) && $upload['error'] != 0) {
                    wp_die('There was an error uploading your file. The error is: ' . $upload['error']);
                } else {
                    add_post_meta($post_id, 'eventEsbat', $upload);
                    update_post_meta($post_id, 'eventEsbat', $upload);     
                } 

            } else {
                wp_die("The file type that you've uploaded is not a PDF.");
            } 

        } 


    }

    public function render_meta_box_content( $post ) {

        wp_nonce_field( 'MetaBoxNonce_action', 'MetaBoxNonce_name' );

        ?>
        <p>pdf file:</p>
        <input type="file" name="eventEsbat" class="eventEsbat" size="25"/>
        <?php
    }
}


function update_edit_form() {
    echo ' enctype="multipart/form-data"';
}

now if in post page I don't upload any file and only make other changes and then click on update or publish button everything goes well and MetaBoxClass::save() will execute.

but if I upload any file then nothing will save even post title don't save too and MetaBoxClass::save() will not execute.

now what section I must to change to solve the problem ?