REST API & localhost CORS error


I have a rest API as a module. My XAMPP installation is running on localhost on port 80. I have a separate vue application running on localhost:8080. I don’t believe I changed anything on my REST API set up, but I noticed in Firefox I can’t get the responses back - 401, this didn’t used to be a probelm until a few days ago. However I think this is a preflight response error. Because I have hard coded the correct auth header into the fetch call. It also works when I’m not accessing through localhost:8080 and postman. I see the OPTIONS request.

So I wondered if somebody may be able to see if there are any errors in my controller set up.

    public static function allowedDomains() {
        return [
            //'*', // star allows all domains

    public function behaviors() {
        $behaviors = parent::behaviors();
        $behaviors['authenticator'] = [
            'class' => HttpBasicAuth::className(),
            'except' => ['login']
        /*$behaviors['access'] = [
            'class' => AccessControl::className(),
        return array_merge($behaviors, [
            // For cross-domain AJAX request
            'corsFilter'  => [
                'class' => \yii\filters\Cors::className(),
                'cors'  => [
                    // restrict access to domains:
                    'Origin'                           => self::allowedDomains(),
                    'Access-Control-Request-Method'    => ['POST', 'GET', 'OPTIONS'],
                    'Access-Control-Allow-Credentials' => true,
                    'Access-Control-Max-Age'           => 3600,   
                    'Access-Control-Allow-Origin' => self::allowedDomains(),
                    'Access-Control-Allow-Headers' => ['Origin', 'X-Requested-With', 'Content-Type', 'accept', 'Authorization'],

I am currently getting

Reason: CORS header ‘Access-Control-Allow-Origin’ missing
Reason: CORS request did not succeed

Thanks :slight_smile: