ASI Driver issue with Windows 11

raul-supernova

Hello
My cameras (ASI 1600MM-Pro and ASI 290mm mini) were working fine until I've tried them this week. It gives a driver error "asicamusb3.sys does not pass the windows driver policy". When I click on learn more it directs me to : https://support.microsoft.com/en-us/windows/the-windows-driver-policy-ecd2a78c-750c-415d-93f2-e37302ce0443 Which esentially highlights drivers not passing the Windows Hardware Compatibility Program.

I've tried reinstalling the latest drivers, restarting the PC several times, disabling windows defender, adding the folder of the drivers to Win Defender exclusion list, etc.

Thanks!

raul-supernova

Fixed.

Had to start with the driver signature enforcement mode (shift click + restart, then troubleshooting, advanced, mode 7).

Once back in windows, open admin prompt and type:
bcdedit /set testsigning on
bcdedit /set nointegritychecks on

Now both ZWO devices show as unknown device type, not as imaging devices but at least they work...

n926DXDO

raul-supernova After this process, do I need to install the drivers and ASIstudio? Or should I install everything before?

R712O2eO

raul-supernova
Thank you IT WORKS!!!!!!!!!!!!WALA AND DOES recognize BOTH CAMERAS WITH PROPER NAMES WOW

Carlos Uriarte707

This is a provisional solution, I think that ZWO will be who applied any solution for a thousands people that use W11 with ASI cameras

n926DXDO

I also have the same problem with my ASI662MC, I tried everything but it is impossible to make the camera connect to the PC with WIN 11, let's hope they fix it soon.

My-Stars

n926DXDO ZWO says they’ll have a fix by next week. Kind of upsetting, cause that leaves the whole weekend blank. Not to mention part of this past week. But I guess we need to learn patience.

raul-supernova

n926DXDO I cant recall to be honest but dont think so. In any case, I imagine there is no harm in reinstalling it just in case.

R712O2eO

n926DXDO
No, you don't have to reinstall nothing.

9kdaM30S

I have had the same thing in windows 11 raul-supernova fix work but ZWO need to update the driver

raul-supernova

9kdaM30S Agreed, but that might take a while... glad it worked. though

38CAzzP2

I have it working now as a result of this thread -- thank you so much @raul-supernova!!

FYI for anyone else: what I did was only the two bcdedit commands (performed from a powershell command prompt run as administrator) and then a system reboot. Upon reboot the camera is recognized and shows up in device manager with the right name. What's more, the utilities I need to drive the camera can see it (NINA, PHD2 etc.).

Given that only the bcdedit commands were needed to fix this, that strongly suggests to me that the driver was signed in the first place with a test key not a production key. If so that's a Very Bad Thing(tm) and ZWO has just gotten away with that for years...but it's still on them to fix it properly even if that guess at root cause isn't right.

Stephen Heliczer

Nope... I have spent hours on this.... NOT fixed for me. None of the above works. I have disabled secure boot in Bios, disabled driver signature enforcement, applied nointegitychecks on and testsigning on in adminn mode command prompt, added folder to Windows Defender. And having to faff about with BitLocker in the process and blocked sign ins... Driver still comes up with ERROR 39 after all this work. Hopefully ZWO can fix the camera drivers! I am currently without my 462mc, 174mm, 585mm, 585mc, 2600mcPro cameras on my brand new top-spec i9 5080 laptop. Three clear nights ahead, no cameras.... 🙁

Ul88SQ64

Stephen Heliczer As I understand it (if you have one) you can connect through an Asiair and you should not have to disable any security in Windows for Deep Sky imaging. For me the problem is I do Solar animations and the Asiair won't handle the fps rates. If anyone else had ideas on this, I am sure they will chime in.
In my opinion ZWO are showing poor form in not putting some formal response here... some posts here are 6 days old! If they don't get this resolved very soon then I am taking my 4 ZWO cameras back to where I bought them from for a refund under "not fit for purpose". I refuse to play around with MS security for a hobby when ZWO should have seen this coming.

Stephen Heliczer

Thanks for your reply... Yep, I need these cameras for Solar. My 2600mcair and 2600mcAir work fine with ASIAir/iPad. But a clear sky for a sunny bank holiday in England is rare, and I really want my high frame-rate 585 and 462 cams to work! Ahh well I am sure ZWO will get it sorted, hopefully v soon... It is certainly boring changing boot security settings in bios and dealing with BitLocker and disabling driver signature enforcement, Defender, writing command lines in cmd, etc etc, to no avail. This hobby is difficult enough already 🙂

6TnSy0Ui

Yesterday 21.5.2026 I sent a mail to info@zwoptical.com asking for a bug fix.
Jo

6TnSy0Ui

I got the following reply:

"Hi,
Thank you for reaching out!
This is a known compatibility issue with the latest driver under Win11. We will fix and resolve it next week, please wait patiently.
Clear Skies!
Mei@ZWO Support Team"

So they say: Next week!

My-Stars

6TnSy0Ui Yeah, I think that’s pretty much the same reply we all got. Hopefully they get a fix out soon.

6TnSy0Ui

Here the workaround from ZWO. Method 1 works for me but requires to know the Bitlocker recovery key:

"We are working as fast as possible to resolve this Windows 11 driver issue.This is not a simple bug, but a system-level compatibility change introduced by recent Windows updates, which requires careful rework and testing on our side. Therefore, it inevitably takes some time to deliver a fully stable fix.
We understand this has been affecting users for several days and that a fix “next week” feels slow—we truly appreciate your patience while our engineers finalize the official solution.
In the meantime, please use one of the two temporary methods below to get your ZWO camera working immediately under Windows 11:

Method 1 (Recommended, single-boot temporary fix)
Hold the Shift key and click Restart in the Windows Start Menu.
Select Troubleshoot > Advanced options > Startup Settings.
Click Restart.
After reboot, press 7 or F7 to select Disable driver signature enforcement.
Windows will start with signature checks off for this session; reconnect your camera.

Method 2 (Test Mode, longer temporary fix)
Reboot and enter BIOS.
Disable Secure Boot, save and exit.
If prompted, enter your 48‑digit BitLocker recovery key.
Open Command Prompt as Administrator, run:
plaintext
bcdedit /set testsigning on
bcdedit /set hypervisorlaunchtype off
Restart your PC, reinstall the ZWO driver, then connect your camera.

Important: These are temporary solutions, valid for Windows X64 only (not ARM64). Some motherboards may re-enable Secure Boot after reboot.
We will notify you immediately once the official fixed driver is released.

Clear Skies!
Mei@ZWO Support Team"

Stephen Heliczer

Thank you Mei. I can confirm that THIS WORKS (for me)
Turn off BitLocker
Turn off internet connection
Reboot and enter BIOS. Disable Secure Boot, save and exit.
Open Command Prompt as Administrator, run:
bcdedit /set testsigning on
bcdedit /set hypervisorlaunchtype off
Restart your PC, reinstall the ZWO driver, then connect your camera

fabianalbertomarin

que porquería lo que esta pasando espero que el fabricante ya tenga todo listo hoy