9 Fixes to SYSTEM THREAD EXCEPTION NOT HANDLED Error in Windows 10/11


Updated on Oct. 27, 2022

Position: Resource - Disk Utilities - 9 Fixes to SYSTEM THREAD EXCEPTION NOT HANDLED Error in Windows 10/11

SYSTEM THREAD EXCEPTION NOT HANDLED is one of the stop codes when the BSOD error happens to Windows 11/10/8 computers. The error indicates system crash and makes computer get stuck in the blue screen reboot loop. Feel this problem tough to solve? Go through this page to learn possible solutions and get the error fixed with ease.

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"Hello everyone, yesterday I was playing games on my laptop, and it suddenly froze. I wait for several minutes but nothing changed. Finally, I force restarted computer, but I got a blue screen with stop code SYSTEM_TREAD_EXCEPTION_NOT_HANDLED (Dxgmms2.sys). I tried restarting computer a couple of times and always got the BSOD. How can I fix the error without reinstalling Windows?"


What does it mean when it says system thread exception not handled? Under normal circumstances, if you press the power button on your desktop or laptop, your computer will boot into Windows OS. However, in some cases, the Windows 11, Windows 10, Windows 8, or Windows 7 are not loaded properly, and a blue screen appears instead. Whether you are a computer expert or not, the BSOD problem happens unpredictably.

On the blue screen, you can see error messages:

"Your PC ran into a problem and needs to restart.
We'll restart for you. For more information about this issue and possible fixes, visit https://www.windows.com/stopcode
If you call a support person, give them this info:


This is one of the typical BSOD stop codes, and it apparently blocks computer from being used. As a result, you cannot access either Windows or personal files on the computer. In some cases, there is a file name appearing together with the stop code "system_thread_exception_not_handled", for example,

  • Atikmdag.sys: This is a graphic driver comes from ATI Radeon Family and it is related to ATI video card. If the AMD graphics card is installed on our computer, drivers for that card might be outdated or incorrect.
  • Nvlddmkm.sys: This is the driver from Nvidia video card and connected to Nvidia Windows kernel driver. If your computer uses Nvidia graphics card, the error code means the drivers are corrupted, outdated or damaged.
  • Dxgmms2.sys: This driver relates to DirectX installed on the computer.
  • Ntfs.sys: It is connected to the system file of Windows NT server. It indicates crashes or errors.
  • Bcmwl63a.sys: This is for Broadcom 802.11 wireless Network Adapter driver.
  • CMUDA.sys: It is associated with the USB audio device. If the driver fails, there might be BSOD issue.
  • Fltmgr.sys: This concerns the Microsoft FileSystem Filter Manager.

What Causes System Thread Exception Not Handled Error?

Before we step forward to fix the error, we'd like to talk about possible reasons behind the error. The causes cannot be determined before analyzing the memory dump file, and yet we will list common causes:

  • There is something wrong with multiple drivers, for example, drivers are corrupted, outdated, damaged, incompatible, etc.
  • Recently installed hardware is not compatible with the computer.
  • Excessive usage of RAM.
  • Buggy system updates.
  • Operating system is unable to deal with something critical.
  • Certain hardware or software is damaged, for example, hard drive bad sectors, corrupted system files.

How Do I Fix the SYSTEM THREAD EXCEPTION NOT HANDLED Error in Windows 11/10/8/7?

Without wasting much time, let's get started to fix the error. The next content includes 9 approaches that take you through to resolve the blue screen error for Windows 11, Windows 10, Windows 8.1, Windows 8 and Windows 7 computers.

Tip: If you've recently installed or connected new hardware device to the computer, such as graphic card, memory, hard disk, etc., then try starting computer after removing the hardware. If newly installed hardware that is not compatible with computer, there is likely to be BSOD problem.

Boot into Safe Mode with Network

First and foremost, we need to access the Safe Mode so that we can carry out various fixes. There are multiple ways of entering Safe Mode, but the computer cannot boot for the moment, so the recommended procedure of booting into Safe Mode is below:

Step 1. Enter WinRE (Windows Recovery Environment).

1. Restart the computer. Press and hold the power button for 10 second as soon as you see Windows gets started or manufacturer's logo presents.

2. Press the power button to turn on computer again. Then press and hold the power button for 10 seconds to turn off computer on the first sign that Windows gets started.

3. Repeat previous steps until you enter WinRE.

Step 2. Boot into Safe Mode.

1. When you see "Choose an option" screen, click Troubleshoot > Advanced options > Startup Settings > Restart.

2. After computer restart, you can see a list of options, see the picture below. To enter Safe Mode with Networking, press F5.


After entering Safe Mode, you can start following fixes.

Method #1: Fix Faulty Drivers

Step 1. Discover which drive is faulty.

1. Right-click Start menu and choose "Event Viewer".

2. Expand "Windows Logs" > "System" on the left pane.

3. Find "system thread exception not handled" or "system_thread_exception_not_handled" in the middle pane and click it to see the problematic driver.

Step 2. Rollback the driver to previous version.

1. Right-click the Start menu and choose "Device Manager" item.

2. Locate and right-click the device in question and choose "Properties".

3. Click "Driver" tab and click "Roll Back Driver" button.

This will roll back to the previously installed drivers. If this method cannot fix the BSOD, then try updating drivers.

Step 3. Update drivers.

1. Open device again and navigate the associated device.

2. Right-click the device and choose "Update driver".


3. On the pop-up window, click "Search automatically for updated driver software".

4. Try searching for updated drivers on Windows Update or on the device manufacturer's website if Windows has determined that the best driver for this device has already been installed.

Method #2: Rename Faulty Files

If updating drivers cannot fix the SYSTEM THREAD EXCEPTION NOT HANDLED error, you can try renaming the file which is associated with the error. Here is how to do so:

Step 1. Double click "This PC" icon to open Windows File Explorer.

Step 2. Open the path "C:\Windows\System32\drivers" and you can see all driver file names.

Step 3. Look for the driver that causing the BSOD stop code. Right-click it and choose "Rename".

Step 4. Add ".old" extension at the end of the file name.

Step 5. Click "Yes" to continue if you are asked to give administrative permission.

Method #3: Scan and Repair Corrupted System Files via SFC

The System File Check (SFC) command can check and repair corrupted system files automatically, and it is quite simple to run SFC.

Step 1. Type cmd in searching box to find Command Prompt. Launch Command Prompt as administrator.

Step 2. Type sfc /scannow and press Enter key.

The scanning may take a couple of minutes, wait with patience please.


Method #4: Check and Repair Bad Sectors for System Disk

It is common that bad sectors bring about BSOD problems. Thus, you may as well check bad sectors for hard drives, SSDs and external hard drives connected to the computer.

DiskGenius Free Edition provides that feature to check or repair bad sectors for both internal and external storage devices. And the software works smoothly in Windows Safe Mode, Windows PE, Windows Server and Windows 11/10/8/7/Vista/XP. Here are steps to check bad sectors:

Step 1. Install and launch DiskGenius Free Edition. Select one of the hard disks or SSDs installed on the software, and click "Disk" – "Verify Or Repair Bad Sectors".


Step 2. Click "Start Verify" button on the pop-up window and the application starts to scan the drive.


Step 3. Wait for the scanning to complete. Do not access the drive during the scanning.


Method #5: Perform a Full Scan for Virus & Threat Protection

Viruses or malware not only threats data safety but also affects OS booting, as critical system files can be destroyed or lost due to virus or malware. Performing a full scan for computer, including operating system, is necessary. Free protection software is built-in Windows, and there is no need to install third-party anti-virus software. Below are steps to scan computer for virus and malicious software:

Step 1. Right-click Start menu and choose "Settings".

Step 2. Click Update & Security > Windows Security > Virus & threat protection > Scan options.

Step 3. Select "Full scan" and click "Scan now". The scanning process may take more than an hour, because it checks all files and running programs on the hard drive.


Method #6: Install System Updates

Sometimes the blue screen is caused by errors in system files, vulnerabilities, or bugs, and you need to try installing the latest system updated to get rid of these issues.

To manually check and install updates, go through steps below:

Step 1. Right-click Start menu to choose "Settings".

Step 2. Click Update & Security > Windows Update > Check for updates.

Step 3. Click "Download and install". Your computer may need to restart to install updated.

Method #7: Run Windows Memory Diagnostic

There is a free RAM testing tool built in Windows 11, Windows 10 and Windows 7 and other modern versions of Windows operating system. Problematic memory can cause computer to stop working or even lose information. Check problems for RAM with steps below:

Step 1. Type "Windows Memory Diagnostic" in the searching box next to the Start menu and click "Run as administrator".

Step 2. Click "Restart now and check for problems".


Method #8: Restore OS to a Previous Time Point

This fix requires that you have a restore point which was created when Windows was running properly. When backups are not available for the moment, move to Method #9.

Step 1. Right-click the Start menu and choose "Settings".

Step 2. When Windows Settings window pops up, type "Recovery" in the searching box and choose "Recovery" from drop-down list.

Step 3. Click "Open System Restore" under advanced recovery tools. This option will undo recent changes, but leave files such as documents, pictures, and music unchanged.

Step 4. Select a restore point and click "Next" button. Then Windows will roll back to the selected point.

Method #9: Reinstall Windows or Reset PC

The last resort to fix the "system thread exception not handled" stop code is reinstalling Windows. It's OK to choose reset PC if you feel it is easier than a clean installation of Windows. Remember to back up files you want to keep to another hard disk before starting reinstalling or resetting Windows.

How to Recover Data When Computer Gets Stuck in SYSTEM THREAD EXCEPTION NOT HANDLED Error?

DiskGenius Professional Edition is capable data recovery software as well as partition manager software. With this tool, you can recover lost files from crashed internal hard drive of desktops or laptops, recover files from RAW partitions, search for deleted or partitions, undelete files from empty Recycle Bin, recover photos from SD cards, recover corrupted USB drive data, and more.

Tip: DiskGenius supports to recover lost files and partitions in Windows Safe Mode. So you can start the data recovery after entering Windows Safe Mode. However, if you cannot access the Safe Mode, you can create a bootable USB drive using DiskGenius. Then boot the crashed computer with the USB drive and start the recovery.

Step 1. Create a bootable USB drive using DiskGenius Free Edition.

1. Insert a USB drive to computer and launch DiskGenius Free Edition.

2. Select the USB drive in the software and click "Tools" – "Create WinPE Bootable USB Drive of DiskGenius".


3. Click "OK" button and wait for several seconds. Then the bootable drive will be created successfully.


After handling the unbootable issue, we can start the data recovery process.

Step 2. Right-click the drive that needs recovering data and choose "Recover Lost Files".


Step 3. Click "Start" button to initiate the scanning process.


Step 4. Wait for the file scanning to finish.

Lost files found during the scanning process are continually added to scanning result.


Step 5. Preview lost files after scanning is done. Previewing files allows you to check the chance of a successful recovery.


Step 6. Copy files you want to restore to a different location.


Frequently Asked Questions

1. Is system thread exception not handled bad?

Yes, it is not good news in most cases. The "System thread exception not handled" error is one of the BSOD stop codes occurred to Windows 8, Windows 10 and Windows 11 computers. It prevents computers from booting into Windows properly. As a result, you cannot access files or even lose important data.

2. How do I run Windows in Safe Mode?

Here are steps to start computer in safe mode in Windows 11/10/8/7:

Step 1. Start menu > Settings > Update & Security > Recovery > Advanced startup > Restart now.

Step 2. Restart computer > Choose an option > Troubleshoot > Advanced options > Startup Settings > Restart.

Step 3. Restart computer > Press F4 for Safe Mode or press F5 for Safe Mode with Networking.

3. How do I fix system service exception in Windows 11?

System service exception is one of the Windows stop codes, and it usually occurs when the hardware or software goes wrong. To fix the error, you can try these tricks: install system updates, update drives, check and repair bad sectors for hard disk, run SFC to fix errors in system files, uninstall recently installed software and hardware, reset Windows OS, etc.

4. How do you fix a bad pool caller?

The "Your PC ran into a problem and needs to restart. We're just collecting some error info, and then we'll restart for you. You can search for the error online. Stop code: BAD_POOL_CALLER" error indicates that configurations of the computer need to be changed to previous status. Here is how to fix the error:

Step 1. Repeat restarting computer until you see the "Please wait" message.

Step 2. Then click Troubleshoot > Advanced options > Startup Settings > Restart.

Step 3. Choose "last known good configuration" during restarting.

Step 4. Open Device Manager > click "Scan for hardware changes". Then restart computer again.

5. Should I switch to Windows 11?

It is worthwhile to upgrade to Windows 11 for most users, for it is designed with new features and better performance. Moreover, there is not that much risk to upgrade to Windows 11, because you can roll back to Windows 10 within a certain period of time. So, you can give it a shot if the hardware of your computer meets the requirements of Windows 11.

6. How long does a Windows system restore take?

The system restore process generally takes around half an hour or longer, and the process can also get stuck if there is something wrong with the hard disk. It is suggested to try some troubleshooting if the restoring process takes over 4 hours and there is not further progress.

7. How do I fix system thread exception not handled Vgk sys?

When your computer gets stuck in vgk.sys BSOD loop, you can try following methods to fix it.

  • Run automatic repair
  • Boot to Safe Mode
  • Uninstall Vanguard
  • Restore Windows to a previous status

8. Why does system service exception happen?

The System Service Exception error can be caused by various reasons for example, corrupted or outdated drives, some applications try to access Windows-protected codes, buggy Windows updated, corrupted system files, cyberattacks, etc.

Further Reading


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