OAuth “Internal error” on first login only when using company Auth0 tenant (Works on personal tenant)

Hi everyone,

I’m using Auth0 as the authentication layer for an application built with the ChatGPT Apps SDK. Everything works correctly when I use my personal Auth0 tenant, but I encounter a consistent issue when using my company’s Auth0 tenant.

Problem Description

When the OAuth flow is initiated from my app:

  1. The user is redirected to Auth0.

  2. They enter their username and password.

  3. After successful authentication, instead of returning to the app, the browser is redirected to:

chatgpt.com/connector_platform_oauth_redirect?error=server_error&error_description=Internal+error&state=oauth_s_691c9a9817c88191a280e93965e37dd2

However:

  • This issue only occurs on the first login attempt for a new or existing user.

  • If the same user tries logging in again immediately afterward, the login succeeds.

  • If the user chooses Sign Up instead of Sign In, the error does not occur at all.

  • The exact same configuration works perfectly on my personal Auth0 tenant, so the client setup itself seems valid.

Auth0 Logs

On the company tenant, I see an Internal error in the Auth0 logs for the failing login. Here is the raw log entry (anonymized where appropriate). Unfortunately, it does not reveal the root cause:

{
  "date": "2025-11-18T16:11:39.684Z",
  "type": "f",
  "description": "Internal error",
  "connection": "Username-Password-Authentication",
  "connection_id": "con_9UcxragsycRyhPie",
  "client_id": "XXXX_XXX",
  "client_name": "ChatGPT",
  "ip": "167.103.88.187",
  "user_agent": "Chrome 142.0.0 / Mac OS X 10.15.7",
  "details": {
    "body": {},
    "qs": {
      "state": "****************************Z3Bu"
    },
    "connection": "Username-Password-Authentication",
    "error": {
      "message": "Internal error",
      "oauthError": "Internal error",
      "type": "server_error",
      "uri": null
    },
    "session_id": "etAMe1j047Z2iyAGHcdsBEUFRCMwY02D",
    "riskAssessment": {
      "confidence": "high",
      "version": "1",
      "assessments": {
        "UntrustedIP": {
          "confidence": "high",
          "code": "not_found_on_deny_list"
        },
        "NewDevice": {
          "confidence": "medium",
          "code": "partial_match",
          "details": {
            "device": "unknown",
            "useragent": "known"
          }
        },
        "ImpossibleTravel": {
          "confidence": "high",
          "code": "minimal_travel_from_last_login"
        },
        "PhoneNumber": {
          "confidence": "neutral",
          "code": "phone_number_not_provided"
        }
      }
    },
    "actions": {
      "executions": [
        "ZTIFtPlmhc5Kl6aeGEo5DWAKMjAyNTExMThGmky8gl9DfY--ltxEPEO8"
      ]
    },
    "stats": {
      "loginsCount": 18
    }
  },
  "hostname": "XXXX_XXX",
  "user_id": "auth0|6916cb85ab8fd0701235ddff",
  "user_name": "XXXX_XXX",
  "strategy": "auth0",
  "strategy_type": "database",
  "audience": "XXXX_XXX",
  "scope": [
    "openid",
    "profile"
  ],
  "environment_name": "XXXX_XXX",
  "tenant_name": "XXXX_XXX"
}

Summary

  • Only the first login fails with a server_error.

  • Subsequent logins succeed.

  • Sign-up flow succeeds.

  • Works fine on my personal Auth0 tenant.

  • Logs show Internal error but no details.

What I’m Looking For

Has anyone seen this pattern before — first-login-only internal errors in Auth0?

Are there known tenant-wide configurations (Actions, Rules, Attack Protection policies, first-login flows, org membership, advanced user profile handling, etc.) that could cause a transient internal error that only occurs on initial login?

Any guidance or next steps for debugging this would be greatly appreciated.

Thanks!

OpenAI has changed their connector, Now we can add Client Id and Client Secret. So, now we can create a first party application in Auth0 tenant and use it for the connector. This prevents multiple dynamically created third party applications in the tenant. It also resolved my previously mentioned login issues.

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