App Login Fails with Code Exchange Unsuccessful Error

Last Updated: Feb 20, 2026

Overview

When trying to login to an app, the following error is received:

Fatal error: Uncaught Auth0\SDK\Exception\StateException: Code exchange was unsuccessful; network error resulted in unfulfilled request in ...

Applies To

Application Login
Client Secrets

Cause

An incorrect Client Secret on the remote server ".env" file.

Solution

Run the Auth0 app locally. This will determine if there is an issue with the remote server.
Confirm that all settings on the server are correct.
Check the client's secret.