Title: Error Code 401 “missing required authentication credential”
Last modified: June 28, 2025

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# Error Code 401 “missing required authentication credential”

 *  Resolved [pwizard](https://wordpress.org/support/users/pwizard/)
 * (@pwizard)
 * [9 months, 2 weeks ago](https://wordpress.org/support/topic/error-code-401-missing-required-authentication-credential/)
 * You asked me to create a new topic on the same unresolved issue that someone 
   else is experiencing.
 * I have to go back in and reset gmail setting and reauth then resend failed emails.
   Nothing to do with passwords as you suggested. Please refer to the same open 
   support discussion.
   { “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](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”: { “service”: “gmail.
   googleapis.com”, “method”: “caribou.api.proto.MailboxService.SendMessage” } }]}}
    -  This topic was modified 9 months, 2 weeks ago by [pwizard](https://wordpress.org/support/users/pwizard/).

Viewing 1 replies (of 1 total)

 *  Plugin Support [M Aqib Khan](https://wordpress.org/support/users/aqibkhan9/)
 * (@aqibkhan9)
 * [9 months, 2 weeks ago](https://wordpress.org/support/topic/error-code-401-missing-required-authentication-credential/#post-18539053)
 * Hello [@pwizard](https://wordpress.org/support/users/pwizard/) ,
 * We hope this message finds you well.
 * Thank you for reaching out to our Support team.
 * The error message you’re encountering, a 401 Unauthorized error from the Gmail
   API, indicates that the request is missing a valid Client ID and Client Secret(
   OAuth 2.0 access token). This typically occurs when OAuth authorization is disrupted.
 * If you recently changed your Gmail account password, please note that this action
   revokes all existing OAuth permissions granted to connected apps. As a result,
   any applications (including Post SMTP) that were previously authorized will be
   disconnected. You’ll need to reconnect Post SMTP by authorizing it again using
   the same email account through the Post SMTP setup wizard.
 * You may follow our detailed [documentation](https://postmansmtp.com/documentation/sockets-addons/gmail/)
   to complete this reauthorization process.
 * However, if you’re confident the issue isn’t related to a password change, we
   may need to explore other potential causes, such as:
    - A conflict with another plugin or theme
    - Browser or site-level caching
    - Expired or incorrect Google Cloud credentials
 * Please let us know how you’d like to proceed. We’re here to assist you every 
   step of the way.
 * Warm regards,
   Support Team – WP Experts

Viewing 1 replies (of 1 total)

The topic ‘Error Code 401 “missing required authentication credential”’ is closed
to new replies.

 * ![](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/)

 * 1 reply
 * 2 participants
 * Last reply from: [M Aqib Khan](https://wordpress.org/support/users/aqibkhan9/)
 * Last activity: [9 months, 2 weeks ago](https://wordpress.org/support/topic/error-code-401-missing-required-authentication-credential/#post-18539053)
 * Status: resolved