Microsoft says devices running unsupported versions of Windows will stop receiving security updates after next year's Windows Update certificate rotation.
To ensure devices keep receiving updates, admins and users must upgrade to a supported version of Windows before the Windows Update certificates expire in May and June 2027.
"As a standard security practice, these certificates have an expiration date. This means that they eventually need to be rotated (that is, replaced by new certificates). A set of these certificates will expire on May 17, 2027 and June 19, 2027," Microsoft said on Thursday.
It also added that devices on unsupported versions of Windows "will lose access to Windows Update services and won't receive any updates as a result" and recommended "upgrading to a supported version of Windows client or server."
In a separate Microsoft 365 Message Center update, it also noted that replacement certificates have already been delivered to systems running a supported Windows version and don't require additional action if they're up to date.
Microsoft shared the following detailed guidance on the required actions by Windows version: