All change for Windows

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In an “important” update last week, Microsoft confirmed that the Secure Boot certificate expiration that starts in June will affect “most Windows devices." To avoid disruption, the company says “take action to update certificates in advance.”

Microsoft says failing to install the latest Windows update, which should refresh your Secure Boot certificates, “might affect the ability of certain personal and business devices to boot securely if not updated in time.” After you update, it’s likely that your PC will undergo a "one time restart" to load new certificates.

In a separate warning, Microsoft warns problems “could occur as early as June." If a security update “cannot be delivered to your device’s current boot configuration," because your PC “has not yet received the updated certificate,” you will see a “Secure Boot badge change to a red stop icon” in the Windows Security app.

Microsoft issued its latest update on May 12. It was then refreshed 24 hours later to add its “Secure Boot release note.” But the update was changed again on May 15, with a warning that this critical update may "fail to install.”

That gives Windows users a dilemma — given the need to ensure the update has been installed on PCs by June 1. Microsoft says the workaround for most users is likely a restart, albeit this will rollback the update. It’s unclear what this means for Secure Boot certificates that are wrapped into the software download.

There is a more nuanced Secure Boot warning in this week’s update as well. “With this update,” Microsoft says, “Windows quality updates include additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates.”

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Not the clearest language for any worried users. And not helped by a cryptic warning that “devices receive the new certificates only after demonstrating sufficient successful update signals, maintaining a controlled and phased rollout."

We will not know how many PCs are affected by this for some time.