gistfile1.txt

if( wp_verify_nonce( $_POST['fileup_nonce'], 'my_file_upload' ) ){

		if ( ! function_exists( 'wp_handle_upload' ) ) {
			require_once( ABSPATH . 'wp-admin/includes/file.php' );
		} 

		// require_once( ABSPATH . 'wp-admin/includes/image.php' );
		// require_once( ABSPATH . 'wp-admin/includes/file.php' );
		// require_once( ABSPATH . 'wp-admin/includes/media.php' );

		$file = & $_FILES['my_file_upload'];
	
		$overrides = [ 'test_form' => false ];
	
		$movefile = wp_handle_upload( $file, $overrides );

		// $attachment_id = media_handle_upload( 'my_file_upload', '0' );

		if ( $movefile['error'] ) {
			update_user_meta( $customer_id, 'uploaded_file', $movefile['error'] );
		}

		if ( $movefile && empty( $movefile['error'] ) ) {
			update_user_meta( $customer_id, 'uploaded_file', $movefile['url'] );
		}
	}