升级PHP 7，WordPress后台空白

最近将环境升级到PHP 7，发现WordPress后台打开空白，开启详细报错后提示wp-includes/user.php这个文件有异常。php

也不知道是否自己WordPress版本（4.3）较低的原因，可以参考如下方法解决。修改wp-includes/user.php这个文件，在

if ( empty($credentials) ) {

后面增加：

$credentials = array(); // 增加这行代码

增加完成后的代码如下，保存后正常。

function wp_signon( $credentials = array(), $secure_cookie = '' ) {
    if ( empty($credentials) ) {
        $credentials = array(); // Back-compat for plugins passing an empty string.
 
        if ( ! empty($_POST['log']) )
            $credentials['user_login'] = $_POST['log'];
        if ( ! empty($_POST['pwd']) )
            $credentials['user_password'] = $_POST['pwd'];
        if ( ! empty($_POST['rememberme']) )
            $credentials['remember'] = $_POST['rememberme'];
    }
 
    if ( !empty($credentials['remember']) )
        $credentials['remember'] = true;
    else
        $credentials['remember'] = false;
 
    /**
     * Fires before the user is authenticated.
     *
     * The variables passed to the callbacks are passed by reference,
     * and can be modified by callback functions.
     *
     * @since 1.5.1
     *
     * @todo Decide whether to deprecate the wp_authenticate action.
     *
     * @param string $user_login    Username, passed by reference.
     * @param string $user_password User password, passed by reference.
     */
    do_action_ref_array( 'wp_authenticate', array( &$credentials['user_login'], &$credentials['user_password'] ) );
 
    if ( '' === $secure_cookie )
        $secure_cookie = is_ssl();
 
    /**
     * Filters whether to use a secure sign-on cookie.
     *
     * @since 3.1.0
     *
     * @param bool  $secure_cookie Whether to use a secure sign-on cookie.
     * @param array $credentials {
     *     Array of entered sign-on data.
     *
     *     @type string $user_login    Username.
     *     @type string $user_password Password entered.
     *     @type bool   $remember      Whether to 'remember' the user. Increases the time
     *                                 that the cookie will be kept. Default false.
     * }
     */
    $secure_cookie = apply_filters( 'secure_signon_cookie', $secure_cookie, $credentials );
 
    global $auth_secure_cookie; // XXX ugly hack to pass this to wp_authenticate_cookie
    $auth_secure_cookie = $secure_cookie;
 
    add_filter('authenticate', 'wp_authenticate_cookie', 30, 3);
 
    $user = wp_authenticate($credentials['user_login'], $credentials['user_password']);
 
    if ( is_wp_error($user) ) {
        if ( $user->get_error_codes() == array('empty_username', 'empty_password') ) {
            $user = new WP_Error('', '');
        }
 
        return $user;
    }
 
    wp_set_auth_cookie($user->ID, $credentials['remember'], $secure_cookie);
    /**
     * Fires after the user has successfully logged in.
     *
     * @since 1.5.0
     *
     * @param string  $user_login Username.
     * @param WP_User $user       WP_User object of the logged-in user.
     */
    do_action( 'wp_login', $user->user_login, $user );
    return $user;
}

此文参考了：PHP7.1环境中,WordPress登录失败