Cursor
auth
OAuth Token Refresh Fails After Cursor AI Refactor
After using Cursor's AI to refactor authentication code, OAuth token refresh requests return 401 Unauthorized errors. The application was previously handling token refresh correctly, but the AI-generated changes broke the flow.
Users are unexpectedly logged out during their sessions, and the app fails to silently refresh expired tokens before making API requests.
Error Messages You Might See
401 Unauthorized
Invalid refresh token
token_expired
refresh_token_revoked
Common Causes
- AI generated incorrect token expiry comparison logic (using < instead of > or vice versa)
- Refresh token endpoint URL was modified incorrectly during refactoring
- Missing token type validation (Bearer token prefix stripped)
- Async/await chain broken, causing refresh to complete after API call
- Removed token storage in localStorage/sessionStorage during cleanup
How to Fix It
Verify the token expiry check uses correct comparison: Date.now() > expiryTime. Check that refresh endpoint matches OAuth provider docs. Ensure Bearer prefix is preserved. Validate token refresh completes before making authenticated requests.
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Get HelpFrequently Asked Questions
Why does my app work in dev but fail in production?
Token expiry times differ between environments. Ensure server time is synced and expiry buffer is adequate (refresh 30s before actual expiry).
How do I debug token refresh?
Add console.log statements before/after refresh call. Check network tab in DevTools for actual refresh request and response.