During the Authorization Code Flow, Auth0 generates a feacft (Failed Exchange: Authorization Code for Token) log when the /oauth/token endpoint request fails. This occurs after a successful login (type:s log). If the feacft log shows null for the client_id or client_name values despite the preceding type:s log containing them, an incorrect Client Secret likely causes the failure. Resolve this issue by ensuring the Client Secret passed to the endpoint matches the configuration in the Auth0 Dashboard.

• Logs
• Authorization Code Flow

The type:s log indicates successful user authentication and authorization code issuance. The subsequent feacft log indicates a failure during the token exchange phase. While temporary server issues or Proof Key for Code Exchange (PKCE) validation failures cause this error, if the preceding type:s log contains application information, but the feacft log shows null for the client_id or client_name values, this suggests an incorrect Client Secret.

To resolve the token exchange failure when application information is null in the log, navigate to the Auth0 Dashboard, locate the application settings, and verify the Client Secret matches the endpoint request.

1. Navigate to the Auth0 Dashboard.
2. Open the application settings and locate the Client Secret.
3. Verify that the application passes the correct Client Secret during the /oauth/token endpoint call to match the value in the Auth0 Dashboard.
4. Update the application configuration with the correct Client Secret if a mismatch occurs.