Next.js Callback 404 Not Found Error

This article explains why a 404 Not Found error may be seen on the /api/auth/callback route when utilizing the nextjs-auth0 library.

• NextJS-Auth0

If the callback looks similar to the following error, with <AUTH0-DOMAIN> being the domain associated with the Auth0 tenant, this error is happening because of the misuse of the Auth0 domain.

https://<AUTH0-DOMAIN>/api/auth/callback

• The Auth0 domain should only be utilized to complete calls towards one of the Auth0-managed APIs
• The error occurs because the /api/auth/callback is not an Auth0 API endpoint, but rather a route in the application.

1. Verify that the environment variable AUTH0_BASE_URL exists within the .env configuration file for applications built with the NextJS-Auth0 SDK.
2. Set the AUTH0_BASE_URL variable to the base URL where the Next.js application is hosted.
   • For local development, this value is typically similar to the following example: http://localhost:3000.
3. Confirm the AUTH0_BASE_URL variable contains the application's hosting URL, not the Auth0 tenant domain.
   • Example of an incorrect value (tenant domain): https://<tenant_name>.<region>.auth0.com/
4. If issues continue, check the configured AUTH0_BASE_URL domain for correct spelling and validity.