A Gmail app password can stop working after it is revoked or the account’s authorization conditions change. Google specifically states that changing the Google Account password revokes existing app passwords. Check the event and client before generating replacements repeatedly.
Identify what the client actually uses
Confirm whether the app uses an app password or Google’s modern sign-in flow. An OAuth connection and a stored app password are different authorization mechanisms, so the same troubleshooting action does not apply to both.
Inspect the exact error. A network timeout, certificate problem, sending restriction, or wrong SMTP host can look like a general connection failure without being an app-password revocation.
Check revocation and account changes
- Review whether the Google password was recently changed.
- Check whether that app password was intentionally removed.
- Confirm the correct account and device.
- For managed mail, ask about relevant administrator restrictions.
If the old secret was lost, Google does not display it again as a normal recoverable password. An eligible account can create a new one through its official controls when genuinely needed.
Replace narrowly or move to modern sign-in
Where the app supports Sign in with Google, prefer that route. If an approved legacy device requires an app password and remains eligible, update only the intended device with the new secret and test harmless mail.
Do not paste the replacement into every connected application indiscriminately. Record which authorized device uses it without exposing the secret. Revoke access for a lost or retired device through the official account interface.
Do not turn off 2-Step Verification or Advanced Protection to revive an obsolete client. Preserve local Drafts and Outbox before removing or re-adding the account.
If failure continues with the supported method, gather the client version, account type, server, and redacted error for trusted support. A replacement secret is not a repair for an unrelated transport, quota, or provider-policy problem, and a successful login alone does not confirm final delivery.
Browse Gmail & Google Account help
References
Reviewed against the linked product guidance, standards, and identified vendor or public-authority guidance on October 29, 2026. Available options and screen labels can vary by account, device, region, and organization policy.