For most Windows users, the act of turning on a computer is an afterthought—a brief pause before the familiar login screen appears. But beginning in June 2026, millions of machines worldwide could greet their owners with something far less welcoming: a black screen, an error message, or simply nothing at all. The culprit is not a virus, not a hardware failure, but an expiring security certificate buried deep in the system’s boot process.
The issue centers on Secure Boot, a foundational security feature built into the UEFI (Unified Extensible Firmware Interface) firmware that underpins virtually every modern PC. Secure Boot ensures that only trusted, digitally signed software can run during the startup process, protecting machines from bootkits and other low-level malware. But the cryptographic certificates that validate this trust have expiration dates—and one critical certificate is set to lapse in 2026, potentially rendering affected systems unbootable.
The
Mechanics of Secure Boot and Why Certificates Matter
As MakeUseOf explained in a detailed breakdown, Secure Boot relies on a chain of trust rooted in cryptographic keys and certificates. When a PC powers on, the UEFI firmware checks the digital signatures of the bootloader and other early-stage software against a database of trusted certificates stored in the firmware. If the signatures match, the system proceeds to load Windows. If they don’t—or if the certificate used to sign the bootloader has expired—the firmware can block the boot process entirely.
Microsoft uses its own certificates to sign Windows bootloaders, and these certificates are embedded in the UEFI firmware of PCs shipped by manufacturers like Dell, HP, Lenovo, and others. The specific certificate at the heart of this looming problem is the Microsoft Windows UEFI CA 2011, which was originally issued with a validity period that extends to 2026. When it expires, any bootloader signed exclusively with this certificate will no longer pass Secure Boot validation on systems that enforce strict certificate checking.
A Problem Years in the Making
This is not a surprise to Microsoft or to the broader PC industry. The expiration date has been known since the certificate was first issued. Microsoft has been working on a transition plan, issuing a newer certificate—the Windows UEFI CA 2023—to replace the aging 2011 version. The challenge lies in the sheer scale of the transition. Hundreds of millions of PCs are currently in use with firmware that only recognizes the old certificate. Updating those machines requires firmware updates from individual PC manufacturers, coordination with Microsoft’s own Windows Update infrastructure, and, in many cases, manual intervention by users or IT administrators.
According to MakeUseOf, Microsoft has already begun rolling out updates that add the new 2023 certificate to the Secure Boot database on supported machines. The company has also started signing its bootloaders with the new certificate. But the transition is far from complete. Machines that have not received these updates—whether because they are running older versions of Windows, have fallen behind on patches, or have firmware that hasn’t been updated by the manufacturer—remain at risk.
Which Machines Are Most Vulnerable?
The PCs most likely to be affected fall into several categories. First and most obviously, machines running Windows 10 are at elevated risk. Microsoft is ending support for Windows 10 in October 2025, just months before the certificate expiration. Users who remain on Windows 10 after that date may not receive the necessary updates to transition to the new certificate, leaving their systems vulnerable to boot failure. Given that Windows 10 still commands a substantial share of the global PC install base—recent estimates from StatCounter suggest it remains on roughly 60% of Windows desktops worldwide—the potential impact is enormous.
Second, older PCs with UEFI firmware that has not been updated by the manufacturer may lack support for the new certificate entirely. Even if Windows itself is updated, the firmware must also recognize the new certificate for Secure Boot to function correctly. Many PC manufacturers stop issuing firmware updates for older models after a few years, effectively orphaning those machines from the certificate transition. Enterprise environments, where hardware refresh cycles can stretch to five or even seven years, are particularly exposed.
The Enterprise Headache
For corporate IT departments, the 2026 certificate expiration represents a significant operational challenge. Large organizations often manage thousands or tens of thousands of PCs, many of which may be running different firmware versions, different Windows editions, and different Secure Boot configurations. Ensuring that every machine in the fleet has both the updated firmware and the updated Windows bootloader is a logistical undertaking that requires careful planning and testing.
The risk is compounded by the fact that Secure Boot failures are not always graceful. Depending on the firmware implementation, a machine that fails Secure Boot validation may display a cryptic error message, drop into a UEFI recovery shell, or simply refuse to power on in any meaningful way. For end users without technical expertise, such failures can be indistinguishable from a dead computer, potentially triggering a wave of support calls and unnecessary hardware replacements.
What Users and Administrators Can Do Now
The most straightforward mitigation is to ensure that all Windows PCs are fully up to date. Microsoft has been delivering the necessary certificate updates through Windows Update, so machines that are current on patches should already have—or will soon receive—the new 2023 certificate in their Secure Boot database. Users should verify that Windows Update is enabled and functioning, and should install any pending updates as soon as possible.
Beyond Windows updates, users should check for firmware updates from their PC manufacturer. This typically involves visiting the support page for the specific PC model and downloading the latest UEFI/BIOS update. As MakeUseOf noted, this step is particularly important for older machines that may not receive firmware updates automatically. Users who are uncomfortable performing firmware updates themselves should seek assistance from a qualified technician, as a failed firmware update can itself render a machine unbootable.
The Nuclear Option: Disabling Secure Boot
For machines that cannot be updated—either because the manufacturer has not released new firmware or because the hardware is too old to support the new certificate—there is a last-resort option: disabling Secure Boot in the UEFI settings. This will allow the machine to boot regardless of certificate status, but it comes with a significant security trade-off. Without Secure Boot, the system is vulnerable to bootkits and other firmware-level attacks that can be extremely difficult to detect and remove.
Disabling Secure Boot may also have downstream consequences. Some features of Windows, including certain aspects of BitLocker drive encryption and Windows Defender’s hardware-based protections, depend on Secure Boot being enabled. Organizations subject to regulatory compliance requirements—such as those in healthcare, finance, or government—may find that disabling Secure Boot puts them out of compliance with security standards. It is a workaround, not a solution, and should be treated as such.
Microsoft’s Broader Security Push and the TPM 2.0 Connection
The certificate expiration issue is intertwined with Microsoft’s broader push to raise the security baseline of the Windows ecosystem. The company’s controversial decision to require TPM 2.0 (Trusted Platform Module) hardware for Windows 11 was driven by similar concerns about firmware-level security. TPM 2.0 works in concert with Secure Boot to provide a hardware-rooted chain of trust, and Microsoft has made clear that it views these technologies as non-negotiable for the future of Windows.
This philosophy has drawn criticism from users and advocates who argue that it effectively forces hardware obsolescence, pushing functional PCs into landfills simply because they lack a specific security chip or an updated firmware certificate. The environmental and economic costs of such forced upgrades are not trivial, particularly in developing markets where older hardware remains in widespread use. Microsoft has countered that the security risks of running unsupported configurations are too great to ignore, but the tension between security and sustainability remains unresolved.
A Ticking Clock for the Industry
With roughly a year remaining before the June 2026 deadline, the window for action is narrowing. Microsoft, PC manufacturers, and IT administrators all have roles to play in ensuring a smooth transition. Microsoft must continue to deliver certificate updates through Windows Update and provide clear guidance to users and enterprises. PC manufacturers must issue firmware updates for as many models as possible, including those that are no longer under active support. And IT administrators must audit their fleets, identify vulnerable machines, and develop remediation plans.
For individual users, the message is simpler but no less urgent: update your PC now, check for firmware updates, and if you are still running Windows 10, begin planning your transition to Windows 11 or an alternative operating system before support ends. The 2026 boot crisis is not inevitable—but avoiding it requires action well before the deadline arrives.
The 2026 Boot Crisis: Why Millions of Windows PCs Could Refuse to Start—and What You Can Do About It first appeared on Web and IT News.