Title: Error Message
Last modified: May 22, 2026

---

# Error Message

 *  [tracydc](https://wordpress.org/support/users/tracydc/)
 * (@tracydc)
 * [6 hours, 23 minutes ago](https://wordpress.org/support/topic/error-message-1085/)
 * My client set up their WP SMTP to forward emails from Gmail to a Yahoo email.
   As far as I can tell, the information they’ve entered for the settings is correct,
   but they keep having failed emails. In the error log, they keep getting messages
   that say:
 * “Mailer: Gmail
   invalid_clientPlease make sure your Google Client ID and Secret
   in the plugin settings are valid. Save the settings and try the Authorization
   again.”
 * We also got a message with error code 401 when UpdraftPlus tried to send an email
   backup:
 * **Heads up!** The last email your site attempted to send was unsuccessful.
 * > Email Source: UpdraftPlus – Backup/Restore Mailer: Google / Gmail { “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.&#8221](https://developers.google.com/identity/sign-in/web/devconsole-project.&#8221);,“
   > 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”}}]}}
 * When we try to use the “Allow plugin to send emails using your Google account”
   button, we get a message that says:
 * “Access blocked: Authorization Error”
 * “Client missing a project id”
 * “Error 401: invalid_client”
 * Can you help me troubleshoot this issue?
 * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Ferror-message-1085%2F%3Foutput_format%3Dmd&locale=en_US)
   to see the link]_

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 * ![](https://ps.w.org/wp-mail-smtp/assets/icon-256x256.png?rev=1755440)
 * [WP Mail SMTP by WPForms - The Most Popular SMTP and Email Log Plugin](https://wordpress.org/plugins/wp-mail-smtp/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/wp-mail-smtp/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/wp-mail-smtp/)
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 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-mail-smtp/unresolved/)
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## Tags

 * [authorization error](https://wordpress.org/support/topic-tag/authorization-error/)
 * [error 401](https://wordpress.org/support/topic-tag/error-401/)

 * 0 replies
 * 1 participant
 * Last reply from: [tracydc](https://wordpress.org/support/users/tracydc/)
 * Last activity: [6 hours, 23 minutes ago](https://wordpress.org/support/topic/error-message-1085/)
 * Status: not resolved