Windows blocking ZWO camera drivers on newer builds

ZWO ASI662MC ZWO ASIStudio CMOS Equipment Beginner Astronomy tools Help Needed Issue report Troubleshooting English
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Interactive Sky avatar
Interactive Sky avatar

Hello everyone,

Has anyone recently encountered Windows blocking ZWO camera drivers?

My ASI662MC suddenly stopped working in:

  • ASIStudio

  • NINA

Windows detects the camera, but Device Manager shows:

  • Code 39

  • “An Application Control policy has blocked this file”

The blocked file is: ASICAMUSB3.sys

📷 image.pngimage.pngI already tried:

  • reinstalling latest ZWO drivers

  • removing old drivers completely

  • disabling Memory Integrity

  • different USB cables/ports

  • USB2 and USB3

I’m on a newer Windows 11 build (26200.x), and after researching it seems Microsoft recently tightened driver enforcement for older cross-signed kernel drivers.

So I’m wondering:

  • Is anyone else seeing this recently with ZWO cameras?

  • Did you find a fix?

  • Are there newer WHCP-signed ZWO drivers available?

At this point it looks more like a Windows security/driver-policy issue than a hardware problem.

Clear skies!

Well written Respectful Engaging
Robert Eder avatar
Robert Eder avatar

Hi,

a friend of mine has the same problem and we found a temporary solution.

Hold down Shift and click Restart from the Start menu

Choose Troubleshoot

Choose Advanced options

Choose Startup Settings

Click Restart

Windows will restart and show a blue Startup Settings menu

On that menu, press F7 once to select: press 7 to Disable driver signature enforcement

Windows will then continue booting with driver signature enforcement disabled and your cameras will connect. You have to do this after every reboot till ZWO gets this fixed.

Windows 11 update KB5092762 is the culprit.

I'm still on Windows 10 btw😊

Robert

Well written Helpful Concise Engaging Supportive
Interactive Sky avatar
Interactive Sky avatar

Robert Eder · May 23, 2026, 06:19 AM

Hi,

a friend of mine has the same problem and we found a temporarily solution.

Hold down Shift and click Restart from the Start menu

Choose Troubleshoot

Choose Advanced options

Choose Startup Settings

Click Restart

Windows will restart and show a blue Startup Settings menu

On that menu, press F7 once to select: press 7 to Disable driver signature enforcement

Windows will then continue booting with driver signature enforcement disabled and your cameras will connect. You have to do this after every reboot till ZWO gets this fixed.

Windows 11 update KB5092762 is the culprit.

I'm still on Windows 10 btw😊

Robert

Hello Robert,

Thank you very much for your advice.

Clear Skies!

Well written Respectful Supportive