504 5.7.4: XOAUTH no longer supported
Your client tried to sign in with XOAUTH, Google's old OAuth 1.0 mechanism, which Gmail has retired in favor of XOAUTH2.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 504 5.7.4
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
504 5.7.4 XOAUTH is no longer supported.
What it means
XOAUTH was Gmail's first OAuth-based sign-in for SMTP and IMAP, built on OAuth 1.0. Google replaced it with XOAUTH2, which uses OAuth 2.0 access tokens, and Gmail now refuses the old mechanism with this reply. Google links it to its OAuth 2.0 documentation for developers. Clients still on XOAUTH need updating to XOAUTH2, or switching to an app password where the account allows one. As with the other 504 reply, Google's current table prints 5.7.40; the June 2025 version read 5.7.4.
Common causes
- An old client or library that still uses XOAUTH (OAuth 1.0).
- Integration code written before Google's move to OAuth 2.0.
How to fix it
- 01Update the client or library to a version that supports XOAUTH2.
- 02For your own code, follow Google's OAuth 2.0 documentation and request OAuth 2.0 tokens.
- 03Where OAuth is not possible, use an app password if the account allows it.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
- Gmail SMTP errors and codes, version of June 2025 (Internet Archive copy)web.archive.org
Related codes
- 504 5.7.4Unrecognized authentication type.Your client asked Gmail to sign in with an authentication mechanism that Gmail does not offer, so the sign-in was refused.
- 504Command parameter not implemented.The server implements the command, but not the particular parameter or option the client asked for with it.
- 5.7.4Security feature not supported.The message or session asked for a security feature, such as a form of secure authentication, that the delivery protocol here cannot support.
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