by Julie Splinters - -



Hello, all. I’m a devoted gamer, which means that my PC is under huge pressure most of the time. I always thought that I take of PC’s optimization up till today. First of all, I installed Windows Updates and used my PC as usually. Then I had a virus on the system, which I managed to remove, at least I think so. Now I’m struggling with the BSOD CMUSBDAC.sys SYSTEM_THREAD_EXCEPTION_NOT_HANDLED. Can’t find anything helpful about this issue. Could you please help?

Solved Answer


SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (CMUSBDAC.SYS) is the latest BSOD, which has been registered on the Windows 10 x64 bit systems at the end of March. The emergence of this bug coincide with the release of Windows 10 Cumulative Update KB4016635, some specialists speculate that the CMUSBDAC.SYS error might have been prompted by some faulty update components. The file CMUSBDAC.SYS is a constituent of Windows OS, which is related to the C-Media USB Audio Class Driver. The file itself can’t be removed or modified in any way because it belongs to the Windows’ I/O subsystem. According to Windows specialists, SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (CMUSBDAC.SYS) may be caused by virus/malware or the damage of C-Media USB Audio Class Driver.

Likewise most of the BSOD, CMUSBDAC.SYS Stop Error may be extremely troublesome, especially if the user is not technology inclined and has only basic knowledge about Windows OS maintenance. The blue screen usually occurs when using a USB Microphone. However, many people reported it to appear while playing games, downloading updates or immediately after rebooting the system. Typically it reoccurs 5 or 6 times a day, which is a lot if we take into account the fact that each emergence of SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (CMUSBDAC.SYS) bug forces the system to restart. Unfortunately, the official fixes are not yet available, but there is something you can try to restore your PC’s health.


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Method 1. Check the system for malware

Since one of the common SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (CMUSBDAC.SYS) error causes is malware or virus infection, check if your operating system does not contain one. For this purpose, use a professional antivirus and make sure that it’s up-to-date. Our recommendation would be Reimage.

Method 2. Reinstall C-Media USB Device Audio Class Driver

Some people have reported that unplugging the USB Microphone helped them to fix the CMUSBDAC.SYS BSOD temporarily. However, if you are using it regularly, then you should fix the C-Media USB Device Audio Class Driver. Try to update it first and then, if the update does not help, reinstall the driver.

  • Right-click Windows key and select Device Manager.
  • Expand the Sound, video and game controllers section and locate C-Media USB Device Audio Class Driver. If it’s not there, look under Audio Inputs and Outputs.
  • Right-click it and select Uninstall.
  • After that, reboot the system.
  • Re-open Device Manager as explained in step 1 and click Actions tab at the top of the screen.
  • Select Scan for Hardware changes.
  • When the scan results are ready, click Install driver. The system now should find the latest compatible of the C-Media USB Device Audio Class Driver automatically. If for some reason this process ends up with the failure, go to the manufacturer’s website and download the drivers manually.

Method 3. Use a System Restore Point

To perform this method, you have to have a System Restore Point created before the emergence of the SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (CMUSBDAC.SYS) error. If you have, then initiate the steps below. If you don’t, then skip this method.

  • Hold power button to turn off your PC and then restart the system.
  • Before Windows logo shows up, press F8 to boot into Safe Mode.
  • Log in to your account if required.
  • Once the system boots up, disable your antivirus.
  • Click Win key and type system restore.
  • Select Create a restore point, select System Restore and hit Next.
  • Select the latest system restore point and click Next.

Method 4. Reinstall Windows 10 OS

We believe that the last thing you desire is to reinstall your operating system due to such a seemingly simple problem as the SYSTEM_THREAD_EXCEPTION_NOT_HANDLED BSOD. Unfortunately, this solution is the last thing that can be offered in case the previous methods did not help. You can find detailed instructions on how to reinstall Windows 10 on the official Microsoft’s website.

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About the author

Julie Splinters - Computer optimization specialist

When it comes to computer optimization, Julie Splinters is the expert. Whether it is a slow smartphone, Windows, Mac or Linux operating system, she will find a solution within minutes.

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