Error establishing a database connection (Cannot modify header information)

Hi,

I’ve a big (database connection) problem after moving my website to a new registrar.

This is the error I get:

Warning: Cannot modify header information – headers already sent by (output started at /home/iphone1q/public_html/wp-config.php:1) in /home/iphone1q/public_html/wp-includes/functions.php on line 3503

Error establishing a database connection

This is the wp-config file:

<?php
/** Enable W3 Total Cache */
define('WP_CACHE', true); // Added by W3 Total Cache

/** Enable W3 Total Cache Edge Mode */
define('W3TC_EDGE_MODE', true); // Added by W3 Total Cache

/**
 * The base configurations of the WordPress.
 *
 * This file has the following configurations: MySQL settings, Table Prefix,
 * Secret Keys, and ABSPATH. You can find more information by visiting
 * {@link https://codex.ww.wp.xz.cn/Editing_wp-config.php Editing wp-config.php}
 * Codex page. You can get the MySQL settings from your web host.
 *
 * This file is used by the wp-config.php creation script during the
 * installation. You don't have to use the web site, you can just copy this file
 * to "wp-config.php" and fill in the values.
 *
 * @package WordPress
 */

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'iphone1q_1');

/** MySQL database username */
define('DB_USER', 'iphone1q_iphone');

/** MySQL database password */
define('DB_PASSWORD', ‘xxxx’);

/** MySQL hostname */
define('DB_HOST', 'localhost');

/** Database Charset to use in creating database tables. */
define('DB_CHARSET', 'utf-8');

/** The Database Collate type. Don't change this if in doubt. */
define('DB_COLLATE', '');

define( 'WP_ALLOW_REPAIR', true );

/**#@-*/

/**
 * WordPress Database Table prefix.
 *
 * You can have multiple installations in one database if you give each a unique
 * prefix. Only numbers, letters, and underscores please!
 */
$table_prefix  = 'wp_';

/**
 * For developers: WordPress debugging mode.
 *
 * Change this to true to enable the display of notices during development.
 * It is strongly recommended that plugin and theme developers use WP_DEBUG
 * in their development environments.
 */
define('WP_DEBUG', false);

/* That's all, stop editing! Happy blogging. */

/** Absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
	define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php')
?>

This is line 3503 in functions.php:
header( 'Content-Type: text/html; charset=utf-8' );

Does someone know what the problem could be?

Many thanks!

Kind regards,
Roy