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Question

code throws error

        $helper = $fb->getRedirectLoginHelper();
        $loginUrl = $helper->getLoginUrl("https://apps.facebook.com/{$appname}/", $permissions);
        echo "<script>window.top.location.href='".$loginUrl."'</script>";

Error

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the url which throws the error is (replaced my appname with appname) :

https://www.facebook.com/v2.7/dialog/oauth?client_id=8651003434372244&state=f2ad3183f9f04355435434534776ae19688ac&response_type=code&sdk=php-sdk-5.3.1&redirect_uri=https%3A%2F%2Fapps.facebook.com%2Fappname%2F&scope=email

full script

     <?php
    require_once  '../../Facebook/autoload.php';
    $fb = new Facebook\Facebook([
      'app_id' => "$appid",
      'app_secret' => "$appsecret",
      'default_graph_version' => 'v2.7',
    ]);
    $helper = $fb->getCanvasHelper();
    $permissions = ['email']; // optionnal
    try {

            $accessToken = $helper->getAccessToken();

    } catch(Facebook\Exceptions\FacebookResponseException $e) {
        // When Graph returns an error
        echo 'Graph returned an error: ' . $e->getMessage();
        exit;
    } catch(Facebook\Exceptions\FacebookSDKException $e) {
        // When validation fails or other local issues
        echo 'Facebook SDK returned an error: ' . $e->getMessage();
        exit;
     }
    if (isset($accessToken)) {

            $accessToken = (string) $accessToken;
            $fb->setDefaultAccessToken($accessToken);

        if (isset($_GET['code'])) {
            header('Location: ./');
        }

        // validating the access token
        try {
            $request = $fb->get('/me');
        } catch(Facebook\Exceptions\FacebookResponseException $e) {
            // When Graph returns an error
            if ($e->getCode() == 190) {
                $helper = $fb->getRedirectLoginHelper();
                $loginUrl = $helper->getLoginUrl("https://apps.facebook.com/{$appname}/", $permissions);
                echo "<script>window.top.location.href='".$loginUrl."'</script>";
                exit;
            }
        } catch(Facebook\Exceptions\FacebookSDKException $e) {
            // When validation fails or other local issues
            echo 'Facebook SDK returned an error: ' . $e->getMessage();
            exit;
        }
        // getting basic info about user
        try {
            $profile_request = $fb->get('/me?fields=name,first_name,last_name,email');
            $user_profile = $profile_request->getGraphNode()->asArray();
        } catch(Facebook\Exceptions\FacebookResponseException $e) {
            // When Graph returns an error
            echo 'Graph returned an error: ' . $e->getMessage();
            $url = "https://apps.facebook.com/{$appname}/";
            echo '<script>window.top.location.href='.$url.'</script>';
            exit;
        } catch(Facebook\Exceptions\FacebookSDKException $e) {
            // When validation fails or other local issues
            echo 'Facebook SDK returned an error: ' . $e->getMessage();
            exit;
        }
        // priting basic info about user on the screen
        //print_r($user_profile);
        // Now you can redirect to another page and use the access token from $_SESSION['facebook_access_token']
    } else {

        $helper = $fb->getRedirectLoginHelper();
        $loginUrl = $helper->getLoginUrl("https://apps.facebook.com/{$appname}/", $permissions);
        echo "<script>window.top.location.href='".$loginUrl."'</script>";
    }

Answer 1

This error was thrown because I have not added my app's canvas url(example https://apps.facebook.com/appname/) in

Facebook Login->settings under Valid OAuth redirect URIs