Title: Error Message
Last modified: May 22, 2026

---

# Error Message

 *  Resolved [tracydc](https://wordpress.org/support/users/tracydc/)
 * (@tracydc)
 * [5 days, 22 hours 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]_

Viewing 1 replies (of 1 total)

 *  Plugin Support [Shawon Chowdhury](https://wordpress.org/support/users/shawon001/)
 * (@shawon001)
 * [2 days, 2 hours ago](https://wordpress.org/support/topic/error-message-1085/#post-18919880)
 * Hi [@tracydc](https://wordpress.org/support/users/tracydc/) ,
   Thanks for reaching
   out, and I am so sorry to hear about the trouble. That error usually means the
   Google OAuth app used by WP Mail SMTP is missing or misconfigured credentials—
   specifically the Client ID, or OAuth consent setup. Please try copying and pasting
   the client ID again from your Google Cloud settings in the way mentioned [here](https://wpmailsmtp.com/docs/how-to-set-up-the-gmail-mailer-in-wp-mail-smtp/#oauth),
   and see how it goes.

Viewing 1 replies (of 1 total)

You must be [logged 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 reply to this topic.

 * ![](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/)
 * [Active Topics](https://wordpress.org/support/plugin/wp-mail-smtp/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/wp-mail-smtp/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/wp-mail-smtp/reviews/)

## Tags

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

 * 1 reply
 * 2 participants
 * Last reply from: [Shawon Chowdhury](https://wordpress.org/support/users/shawon001/)
 * Last activity: [2 days, 2 hours ago](https://wordpress.org/support/topic/error-message-1085/#post-18919880)
 * Status: resolved