Troubleshooting OAuth Redirects to Incorrect Strava App in Flask-Based Web Application

If you’re developing a web application that integrates with the Strava API for user authentication, encountering unexpected redirect behavior can be perplexing. A common issue faced by developers is when the OAuth authorization flow redirects users to a different application’s authorization page, leading to authentication failures and confusion.

Understanding the Issue

Imagine you’ve set up your Flask backend to initiate the OAuth process using your specified Client ID. However, instead of redirecting users to authenticate with your app, the browser loads an authorization page for a completely unrelated app—such as “Simon’s Journey Viz”—which has its own credentials, description, and scopes. This mismatch can disrupt the login flow and make user management confusing.

Steps to Troubleshoot

1. Verify Your Client ID and Secret:
   Ensure that the Client ID you’re embedding in your authorization URL matches exactly what is listed in your Strava developer dashboard for your intended application. Double-check for typos or accidental copy-paste errors.

2. Check Your Application Configuration:
   Review your app.py or equivalent configuration files to confirm you’re loading the correct credentials. Sometimes, environment variables or config files may point to outdated or incorrect app credentials.

3. Review the Authorization URL Construction:
   Make sure that your Flask app constructs the OAuth URL using the correct Client ID and redirect URI. Here’s a simplified example:
   python
auth_url = (
"https://www.strava.com/oauth/authorize"
"?client_id={client_id}"
"&redirect_uri={redirect_uri}"
"&response_type=code"
"&scope={scopes}"
).format(
client_id=YOUR_CLIENT_ID,
redirect_uri=YOUR_REDIRECT_URI,
scopes='read,activity:read'
)

4. Clear Browser Cache and Cookies:
   Browsers can sometimes cache authorization pages or redirects. Clearing cache ensures you’re seeing the most recent flow.

5. Investigate Strava Developer Dashboard Limitations:
   Notice if you’re unable to modify or delete existing applications. This could hint at account restrictions or a need to contact Strava support.

6. Check for Coincidence or Server-Side Caching:
   If you’re deploying via a platform that caches DNS, redirects, or even server configurations, review these settings as they could cause old or wrong app data to appear.

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