Windows PCs missing key updates could lose security fixes in 2027
Microsoft warns outdated Windows PCs may lose Windows Update and security fixes when certificates expire in 2027.
Microsoft is warning that certificates used to verify Windows Update servers expire on May 17 or June 19, 2027, depending on the Windows version. Devices that do not receive replacement certificates will lose access to Windows Update, including security fixes. Windows 11 version 25H2 and later need no action, version 24H2 needs the September 2025 security update or later, and several other supported versions need the July 2026 update or later. Devices updated through WSUS are excluded, and systems that miss the deadline can still install the required update from the Microsoft Update Catalog.
- Windows Update certificates expire on May 17 or June 19, 2027.
- Devices missing replacements lose Windows Update security fixes.
- Windows 11 25H2 needs no action; 24H2 needs the September 2025 update.
- Several other supported versions need the July 2026 update or later.
- WSUS-managed devices are excluded from this certificate rotation.
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Microsoft is advising users and businesses to update Windows devices before digital certificates used to verify Windows Update servers expire in May and June 2027.
The certificates expire on May 17 or June 19, depending on the Windows version. Devices without replacement certificates will lose access to Windows Update, including security fixes delivered through the service. Microsoft is distributing the replacements through a process known as certificate rotation.
“However, the key to getting updates from Windows Update beyond 2027 is to keep your devices up to date today,” Microsoft’s Andrew Brown said.
Who needs to take action
Most users running a supported Windows version and installing monthly updates should receive the replacement certificates automatically. Some versions require action from IT administrators.
Supported systems that have fallen behind need the required security update. Microsoft advises users with unsupported versions to upgrade.
Windows 11 version 25H2 and later require no action. Version 24H2 needs the September 2025 security update or a later release. Several other supported versions need the July 2026 update or later.
What happens if the deadline is missed
Supported systems can regain access after the deadline by installing the required update. Administrators can download it from the Microsoft Update Catalog or distribute it through their management tools.
Devices receiving updates through Windows Server Update Services, or WSUS, are excluded from this change.
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