Did something on your Windows 11 PC suddenly stop working?

• A backup app — Macrium Reflect, Acronis Cyber Protect, NinjaOne Backup, or UrBackup Server — started failing in April 2026 or later.
• An external USB device that worked yesterday now shows a yellow exclamation mark in Device Manager (the Windows tool that lists all your hardware; open it by pressing the Windows key and typing "Device Manager").
• A piece of hardware — lab instrument, audio interface, programmer dongle, legacy peripheral — lost its driver after a Windows Update.
• Windows shows a message about a driver being "blocked from loading" or pointing at a file ending in .sys.

Microsoft shipped a security policy update on April 14, 2026 — Windows Update package KB5083769 — that added several older device drivers to a "vulnerable driver blocklist." Hardware that worked fine before now refuses to load.

This is documented on Microsoft's own support pages. It is not a problem with your computer, not a problem with your device, and not your fault.

• Wait for a vendor patch.Big-name vendors (Macrium, Acronis, NinjaOne, UrBackup) are actively working on fixed drivers. Check the support page for the app or device that's broken.
• If it's business-critical, get technical help. This site has a deeper explanation page (/pattern) and a tools pack for engineers (/toolkit). Forward the link to your IT team, your developer, or the hardware vendor's support engineer.
• If you're technical yourself, read /pattern for the full explanation, then run the free PowerShell diagnostic on the homepage.

The issue may be something else. A few generic next steps:

• Try Windows Safe Mode to confirm whether the problem is driver-related.
• Check the official support page of the device or app vendor.
• Look through recent Windows Update history (Settings → Windows Update → Update history) for other cumulative updates that might be involved.