Facebook OAuth with Appwrite Cloud fails: "Something went wrong" after login redirect

Troubleshooting Facebook OAuth with Appwrite Cloud: 'Something went wrong' after redirect

Learn how to diagnose and resolve common issues when integrating Facebook OAuth with Appwrite Cloud, specifically the 'Something went wrong' error after login redirect in Flutter/Dart applications.

Integrating third-party authentication like Facebook OAuth into your Flutter application using Appwrite Cloud can sometimes lead to unexpected errors. A common issue developers encounter is a generic 'Something went wrong' message immediately after the user attempts to log in via Facebook and is redirected back to the app. This article will guide you through the typical causes of this problem and provide step-by-step solutions to get your Facebook OAuth working seamlessly with Appwrite.

Understanding the Facebook OAuth Flow with Appwrite

Before diving into troubleshooting, it's crucial to understand the standard flow of Facebook OAuth when integrated with Appwrite. This helps in pinpointing where the process might be breaking down.

sequenceDiagram
    participant User
    participant FlutterApp
    participant AppwriteSDK
    participant AppwriteServer
    participant Facebook

    User->>FlutterApp: Initiates Facebook Login
    FlutterApp->>AppwriteSDK: `account.createOAuth2Session('facebook')`
    AppwriteSDK->>AppwriteServer: Request OAuth2 session
    AppwriteServer->>Facebook: Redirects user for authorization (with `redirectUrl`)
    Facebook-->>User: Presents login/consent screen
    User->>Facebook: Grants/Denies permissions
    Facebook-->>AppwriteServer: Redirects back with `code` or `error` (to `redirectUrl`)
    AppwriteServer->>AppwriteSDK: Processes Facebook response, creates session
    AppwriteSDK-->>FlutterApp: Returns session or error
    FlutterApp-->>User: Displays success or 'Something went wrong'

Facebook OAuth2 Flow with Appwrite

The 'Something went wrong' error typically occurs after the user has successfully authenticated with Facebook and Facebook attempts to redirect back to Appwrite. This suggests an issue with the redirect URL, Appwrite's configuration, or how the Appwrite SDK handles the incoming response.

Common Causes and Solutions

Several factors can lead to the 'Something went wrong' error. Let's explore the most frequent culprits and how to address them.

1. 1. Incorrect Redirect URLs in Facebook Developer Console

This is by far the most common reason. Facebook needs to know exactly where to send the user back after authentication. If the URL doesn't match what Appwrite expects, the process breaks.

Solution:

1. Go to your Facebook Developer App Dashboard.
2. Select your app.
3. Navigate to Facebook Login -> Settings.
4. Ensure that the Valid OAuth Redirect URIs field contains the correct Appwrite OAuth redirect URL. For Appwrite Cloud, this is typically https://cloud.appwrite.io/v1/account/sessions/oauth2/callback/facebook.
5. If you are self-hosting Appwrite, it would be https://[YOUR_APPWRITE_DOMAIN]/v1/account/sessions/oauth2/callback/facebook.

2. 2. Incorrect Redirect URLs in Appwrite Console

Appwrite also needs to know which URLs are valid for your application to redirect to after a successful OAuth flow. This is crucial for security.

Solution:

1. Go to your Appwrite Console.
2. Select your project.
3. Navigate to Auth -> Providers.
4. Find the Facebook provider and click on it.
5. Under App Domains and Redirect URLs, ensure that all URLs your Flutter app might use for redirection are listed. For Flutter, this often includes custom schemes like [YOUR_APP_SCHEME]:// or [YOUR_APP_SCHEME]://oauth2redirect. Example for Flutter Deep Linking: If your app uses myapp://oauth2redirect, add myapp:// and myapp://oauth2redirect to the list.

3. 3. Missing or Incorrect Facebook App ID/Secret in Appwrite

Appwrite uses your Facebook App ID and App Secret to communicate securely with Facebook's API. Any mismatch will cause authentication to fail.

Solution:

1. In your Facebook Developer App Dashboard, go to Settings -> Basic to find your App ID and App Secret.
2. In your Appwrite Console, navigate to Auth -> Providers.
3. Click on the Facebook provider.
4. Verify that the App ID and App Secret fields exactly match those from your Facebook Developer Console. Ensure the provider is enabled.

4. 4. Deep Linking Configuration in Flutter

For Flutter apps, handling the redirect back from Appwrite (which itself receives the redirect from Facebook) requires proper deep linking setup. If your app doesn't correctly capture the incoming URL, the OAuth flow will fail.

Solution:

• Android: Ensure your AndroidManifest.xml has an <intent-filter> for your custom scheme and host. For example:

  <activity ...>
      <intent-filter>
          <action android:name="android.intent.action.VIEW" />
          <category android:name="android.intent.category.DEFAULT" />
          <category android:name="android.intent.category.BROWSABLE" />
          <data android:scheme="[YOUR_APP_SCHEME]" android:host="oauth2redirect" />
      </intent-filter>
  </activity>
  

• iOS: Configure your Info.plist with a URL Scheme. For example:

  <key>CFBundleURLTypes</key>
  <array>
      <dict>
          <key>CFBundleTypeRole</key>
          <string>Editor</string>
          <key>CFBundleURLSchemes</key>
          <array>
              <string>[YOUR_APP_SCHEME]</string>
          </array>
      </dict>
  </array>
  

• Flutter Code: Use a package like uni_links or app_links to listen for incoming deep links and pass them to the Appwrite SDK's account.createOAuth2Session method's success and failure URLs. The success and failure URLs in the Appwrite SDK call should match your deep link scheme, e.g., myapp://oauth2redirect.

Example Flutter Code for Facebook OAuth

Here's a basic example of how you might initiate Facebook OAuth in your Flutter application using the Appwrite SDK, including handling the redirect URLs.

import 'package:appwrite/appwrite.dart';
import 'package:flutter/material.dart';
import 'package:uni_links/uni_links.dart';

class AuthService {
  final Client client = Client()
      .setEndpoint('https://cloud.appwrite.io/v1') // Your Appwrite Endpoint
      .setProject('YOUR_PROJECT_ID'); // Your Project ID

  late final Account account;

  AuthService() {
    account = Account(client);
  }

  Future<void> signInWithFacebook(BuildContext context) async {
    try {
      // Define your deep link scheme for success and failure redirects
      const String successUrl = 'myapp://oauth2redirect';
      const String failureUrl = 'myapp://oauth2redirect';

      await account.createOAuth2Session(
        provider: 'facebook',
        success: successUrl,
        failure: failureUrl,
      );

      // Listen for the incoming deep link after OAuth completes
      // This part is crucial for mobile apps to capture the redirect
      getUriLinksStream().listen((Uri? uri) {
        if (uri != null) {
          // Handle the URI, e.g., navigate to home screen
          print('Received deep link: $uri');
          if (uri.toString().startsWith(successUrl)) {
            // Successfully logged in
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(content: Text('Facebook login successful!')),
            );
            // Navigate to your app's main screen
          } else if (uri.toString().startsWith(failureUrl)) {
            // Login failed
            ScaffoldMessenger.of(context).showSnackBar(
              const SnackBar(content: Text('Facebook login failed.')),
            );
          }
        }
      }, onError: (err) {
        print('Error receiving deep link: $err');
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error during Facebook login: $err')),
        );
      });

    } on AppwriteException catch (e) {
      print('Appwrite Exception: ${e.message}');
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Facebook login failed: ${e.message}')),
      );
    } catch (e) {
      print('General Exception: $e');
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('An unexpected error occurred: $e')),
      );
    }
  }
}

// Example usage in a widget:
// ElevatedButton(
//   onPressed: () => AuthService().signInWithFacebook(context),
//   child: const Text('Login with Facebook'),
// ),

Flutter code to initiate Facebook OAuth with Appwrite and handle deep links.

Advanced Troubleshooting Tips

If the above solutions don't resolve your issue, consider these advanced steps:

1. 1. Check Appwrite Server Logs

If you are self-hosting Appwrite, check the Docker container logs for the appwrite/appwrite service. Look for errors related to OAuth, Facebook, or redirects. These logs often provide detailed error messages that are not exposed to the client.

docker logs appwrite

2. 2. Verify Facebook App Status

Ensure your Facebook app is live and not in development mode, especially if you're testing with users who are not listed as developers, testers, or administrators in your Facebook app roles. Go to your Facebook Developer App Dashboard -> App Review -> Current Version and check the status.

3. 3. Test with a Web Browser

If possible, try initiating the OAuth flow from a web browser (e.g., using the Appwrite Web SDK or directly constructing the OAuth URL). This can help isolate if the issue is specific to the Flutter mobile environment or a more general configuration problem.

4. 4. Clear Browser/App Cache

Sometimes, cached data in the browser (used for the OAuth flow) or your app can interfere. Try clearing your browser's cache/cookies or uninstalling and reinstalling your Flutter app.

By systematically checking these configurations and understanding the OAuth flow, you should be able to resolve the 'Something went wrong' error and successfully integrate Facebook OAuth with your Appwrite Cloud project in your Flutter application.