Firebase Auth Invalid continue URL error when using Firebase Auth.

Understanding Firebase Auth

Firebase Authentication is a comprehensive authentication system that supports various authentication methods, including email/password, phone number, and federated identity providers like Google, Facebook, and Twitter. It is designed to make it easy for developers to add secure authentication to their applications without needing to manage the complexities of authentication protocols.

Identifying the Symptom

When using Firebase Auth, you might encounter the error code auth/invalid-continue-uri. This error typically appears when attempting to redirect users to a specific URL after a successful authentication process. The error message indicates that the continue URL provided in the request is invalid.

Exploring the Issue

The auth/invalid-continue-uri error occurs when the continue URL, which is supposed to redirect users after authentication, is not properly formatted or is not a valid URL. This can happen if the URL is malformed, contains illegal characters, or is not whitelisted in your Firebase project settings.

Common Causes

• Malformed URL: The URL might be missing necessary components such as the protocol (http/https) or domain.
• Unwhitelisted URL: The URL is not included in the list of authorized domains in your Firebase project settings.

Steps to Fix the Issue

Step 1: Verify the URL Format

Ensure that the continue URL is correctly formatted. It should include the protocol (e.g., https://) and a valid domain. Use a URL validator tool to check the format.

Step 2: Whitelist the Domain

Go to your Firebase console and navigate to Authentication > Sign-in method. Under the Authorized domains section, ensure that the domain of your continue URL is listed. If not, add it to the list.

Step 3: Update the Code

Review your code to ensure that the continue URL is being passed correctly. Here's an example of how to set the continue URL in a Firebase Auth request:

firebase.auth().signInWithRedirect(provider).then(function() { return firebase.auth().getRedirectResult();}).then(function(result) { if (result.credential) { // This gives you a Google Access Token. var token = result.credential.accessToken; // The signed-in user info. var user = result.user; // Redirect to the continue URL window.location.assign('https://yourapp.com/continue'); }}).catch(function(error) { console.error(error);});

Additional Resources

For more information on handling Firebase Auth errors, visit the Firebase Auth Error Documentation. To learn more about configuring authorized domains, check out the Firebase Redirect Best Practices.