Title: Possible token refresh issue
Last modified: August 17, 2026

---

# Possible token refresh issue

 *  Resolved [madhazelnut](https://wordpress.org/support/users/madhazelnut/)
 * (@madhazelnut)
 * [3 days, 13 hours ago](https://wordpress.org/support/topic/possible-token-refresh-issue/)
 * Suddenly emails from a PostSMTP/Gmail site stopped arriving. Inspection showed:
 *     ```wp-block-code
       { "error": { "code": 401, "message": "Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.", "errors": [ { "message": "Login Required.", "domain": "global", "reason": "required", "location": "Authorization", "locationType": "header" } ], "status": "UNAUTHENTICATED", "details": [ { "@type": "type.googleapis.com/google.rpc.ErrorInfo", "reason": "CREDENTIALS_MISSING", "domain": "googleapis.com", "metadata": { "method": "caribou.api.proto.MailboxService.SendMessage", "service": "gmail.googleapis.com" } } ] } } 
       ```
   
 * The client-id/secret pair is still in place as I last left it, hence the title
   of this ticket.

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Thread Starter [madhazelnut](https://wordpress.org/support/users/madhazelnut/)
 * (@madhazelnut)
 * [3 days, 13 hours ago](https://wordpress.org/support/topic/possible-token-refresh-issue/#post-18995450)
 * Reproducible (at least) with 3.9.2 and 3.9.5
 *  Thread Starter [madhazelnut](https://wordpress.org/support/users/madhazelnut/)
 * (@madhazelnut)
 * [3 days, 11 hours ago](https://wordpress.org/support/topic/possible-token-refresh-issue/#post-18995538)
 * Closing as user error. Google Cloud App was not completely configured / production
   mode.
 *  Plugin Support [M Aqib Khan](https://wordpress.org/support/users/aqibkhan9/)
 * (@aqibkhan9)
 * [3 days, 11 hours ago](https://wordpress.org/support/topic/possible-token-refresh-issue/#post-18995555)
 * Hi [@madhazelnut](https://wordpress.org/support/users/madhazelnut/) ,
 * It does appear that the issue may be related to expired or invalidated OAuth 
   tokens.
 * As a next step, please generate a new Client Secret in your Google Cloud Console
   and reconfigure the Gmail API authentication in Post SMTP using the updated credentials.
   Once the new credentials are entered, please re-authenticate the Gmail account.
 * After completing the setup, please test sending an email and let us know whether
   the issue persists.
 * If you continue to experience the “401 UNAUTHENTICATED” error, please share the
   Diagnostic Test Report with us so we can investigate further.

Viewing 3 replies - 1 through 3 (of 3 total)

You must be [logged in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fpossible-token-refresh-issue%2F%3Foutput_format%3Dmd&locale=en_US)
to reply to this topic.

 * ![](https://ps.w.org/post-smtp/assets/icon-128x128.gif?rev=3209655)
 * [Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App](https://wordpress.org/plugins/post-smtp/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/post-smtp/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/post-smtp/)
 * [Active Topics](https://wordpress.org/support/plugin/post-smtp/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/post-smtp/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/post-smtp/reviews/)

 * 5 replies
 * 2 participants
 * Last reply from: [M Aqib Khan](https://wordpress.org/support/users/aqibkhan9/)
 * Last activity: [3 days, 11 hours ago](https://wordpress.org/support/topic/possible-token-refresh-issue/#post-18995555)
 * Status: resolved