The “System Thread Exception Not Handled” error is a common Blue Screen of Death (BSOD) on Windows 10 and 11. It appears suddenly, often during startup, and causes the system to crash. This error usually involves malfunctioning drivers or system components. Fortunately, several fixes can help resolve the issue effectively.
The BSOD may also show file names like nvlddmkm.sys, which hint at specific driver faults. These names can help identify the hardware or software causing the crash. Though alarming, this issue is not uncommon and is usually fixable. A structured approach can restore system stability in most cases.
Reasons behind this Error
This section outlines the most common causes behind the error, ranging from faulty drivers to BIOS misconfigurations.
1. Outdated or Corrupt Drivers
Drivers allow communication between Windows and hardware devices like GPUs and network adapters. When these drivers are outdated, corrupted, or incorrectly installed, they can cause critical failures. This often leads to a system thread exception not handled error, prompting Windows to display a BSOD to prevent further damage or instability. Updating or reinstalling drivers often resolves the conflict completely.
2. Damaged System Files
System files are essential for maintaining Windows operations and boot processes. If they are damaged by malware, power outages, or failed updates, they can cause BSOD errors. Windows cannot function correctly without these vital components, leading to exceptions. Repairing them using built-in utilities can often solve the issue.
3. Incompatible Software
Newly installed software, especially system utilities or antivirus tools, may conflict with Windows operations. These applications sometimes interfere with drivers or memory functions, triggering crashes. If the BSOD started after a software installation, that app could be the cause. Removing or updating it might prevent further errors.
4. BIOS Misconfigurations
Incorrect BIOS settings such as altered RAM timing, secure boot, or virtualization can trigger system errors. An outdated BIOS may also not support newer drivers or hardware combinations. These inconsistencies often cause system instability during startup or operation. Resetting BIOS settings to default can sometimes resolve these conflicts.
How to Identify the Issue?
Before applying fixes, use these techniques to diagnose the root cause of the BSOD and gather actionable information.
1. Note the Error Code
When the error occurs, the BSOD often includes a filename or error code that reveals the cause. The system thread exception not handled message typically appears alongside these identifiers, pointing to the specific driver or system component involved. For example, dxgmms2.sys relates to graphics drivers, helping you narrow the search. Always take note of this information before the PC restarts.
2. Boot in Safe Mode
Safe Mode allows the system to boot using only essential drivers and services. If your PC runs normally in Safe Mode, the problem likely lies with third-party software or drivers. This mode provides a stable environment for troubleshooting and repairs. You can uninstall problematic updates or apps from here safely.
3. Check the Event Viewer
Event Viewer logs all significant system events, including crashes and BSODs. By navigating to Windows Logs > System, you can locate critical errors around the time of the crash. These logs often specify the failing driver or hardware component. This insight is crucial for narrowing down the cause efficiently.
4. Run a Memory Test
Faulty RAM can produce symptoms similar to driver failures, such as system crashes. Windows includes a built-in memory diagnostic tool accessible by running mdsched.exe. The system will check for errors during reboot and display results after the scan. If issues are detected, replacing or reseating RAM modules may help.
Ways to Fix the Error
The following nine methods address the most common causes of the error and offer effective solutions to resolve it.
1. Update Problematic Drivers
Updating drivers is one of the most effective solutions to BSODs. Use Device Manager to check for outdated or faulty drivers. Alternatively, download the latest versions directly from the hardware manufacturer’s website. Always restart the system after applying driver changes.
Graphics, network, and audio drivers should be updated first. These are the most common sources of system thread exceptions. Avoid using unverified third-party tools for driver management. Stick with official sources to prevent installing incompatible software.
2. Boot into Safe Mode
Safe Mode allows you to make changes without triggering the crash. It’s useful if the BSOD prevents normal startup. Once in Safe Mode, remove recently added drivers or software. You can also perform a System Restore if needed from this environment.
Access Safe Mode via Recovery Mode or installation media. Choose “Enable Safe Mode with Networking” for internet access. This lets you download tools or updates for troubleshooting. Safe Mode helps confirm if third-party programs are the root cause.
3. Reinstall Graphics Drivers
Graphics drivers are common culprits for this BSOD. Use a tool like Display Driver Uninstaller (DDU) to remove them completely. Then reinstall the latest driver version from AMD, NVIDIA, or Intel. Always install cleanly rather than over the existing one.
Reinstallation ensures that any corrupted files or settings are removed. It’s important to match the driver version with your hardware and Windows version. Avoid beta drivers unless you’re testing intentionally. Restart the PC to finalize changes and test stability.
4. Disable Fast Startup
Fast Startup allows Windows to boot faster but may reload faulty drivers. Disabling it can solve some startup-related BSODs. Go to Control Panel > Power Options > Choose what the power buttons do. Then uncheck “Turn on fast startup” and save your settings.
With Fast Startup off, Windows performs a full boot each time. This helps reset driver states and avoid residual conflicts. If the BSOD disappears, keep Fast Startup disabled for now. It’s a simple change that can have significant effects on system behavior.
5. Run System File Checker
System File Checker (SFC) can detect and repair corrupted Windows files. Open Command Prompt as administrator and run sfc /scannow. Let the process complete without interruption. If issues are found, SFC will attempt to repair them automatically.
If SFC doesn’t fix the problem, try DISM /Online /Cleanup-Image /RestoreHealth. This scans the system image and corrects deeper issues. Combined, these tools are powerful repair utilities. Always restart your PC after running either command for changes to take effect.
6. Roll Back Recent Updates
Some Windows or driver updates may cause instability. Roll them back if the BSOD appeared after an update. Go to Settings > Windows Update > Update History, then uninstall recent changes. In Device Manager, you can also roll back individual driver versions.
System restore points created before updates can also be used. Reverting to a previous system state often resolves post-update issues. Be cautious when accepting new updates until the issue is stable. Delay future updates if they are not critical or security-related.
7. Perform System Restore
System Restore lets you undo recent changes without affecting personal files. It’s an effective way to revert faulty updates or installations. Launch it by searching “System Restore” in the Start Menu. Choose a restore point before the issue started and proceed.
This feature can resolve crashes caused by driver or software changes. It won’t delete documents or photos, only apps and settings. Use it regularly by ensuring restore points are enabled. It’s a simple, safe tool that can save hours of manual troubleshooting.
8. Reset or Reinstall Windows
As a last resort, reset or reinstall Windows to eliminate stubborn issues. Choose Settings > Recovery > Reset this PC and select whether to keep your files. This will remove all drivers and software, restoring a clean system environment.
A full reinstall is effective for deep-rooted problems that defy fixes. Always back up important data before proceeding. After resetting, reinstall only essential apps and drivers first. Monitor system behavior before restoring full functionality.
9. Recover Lost Files in Crash
BSODs may result in unexpected data loss, especially when they occur during critical operations. WinfrGUI, a user-friendly interface for Windows File Recovery, offers a reliable solution for retrieving lost files. It is recommended to install WinfrGUI on a different drive to avoid overwriting deleted data. Once installed, use it to perform a thorough scan of the affected partitions.
Time is an important factor because recovery becomes more difficult the longer data remains unrecovered. Avoid writing new files to the damaged partition before completing the recovery process. Always create a backup of essential files before making major system changes. With WinfrGUI, you can effectively reduce the impact of system crashes and restore valuable data.
Seek Professional Help
If none of the above fixes work, it’s time to call a professional. Technicians have access to tools that can diagnose complex hardware or software faults. They can test components like RAM, hard drives, or the motherboard directly. This is often the safest option for persistent BSODs.
Delaying expert help can lead to worsening system damage. Repeated crashes stress your components and may corrupt your storage. Technicians can also help recover lost data and reinstall Windows cleanly. Their experience speeds up resolution and ensures long-term system health.
Future Precautions
To minimize the risk of future BSODs, apply these long-term preventive practices for better system health.
1. Keep Drivers Updated
Always keep your drivers up to date using official tools. GPU and chipset drivers, in particular, should never be outdated. Tools like GeForce Experience and Intel Driver Assistant make this easy. Schedule regular monthly checks to stay protected from driver-related errors.
2. Avoid Overclocking
Overclocking increases performance but reduces system stability. Reset your BIOS settings to default if BSODs appear after overclocking. Only experienced users with advanced cooling setups should attempt it. Even then, do so with caution and proper monitoring tools.
4. Enable System Restore
Ensure System Restore is turned on for your system drive. It can save your system from disaster after failed updates or installations. Create a restore point before making major changes. This simple habit provides peace of mind and easy recovery when needed.
5. Backup Important Data
Regularly back up your files to cloud storage or external drives. Tools like OneDrive and File History make this process automatic. In the event of a crash, you’ll avoid permanent data loss. Always keep at least one backup copy stored separately from your device.
Final Thoughts
The “System Thread Exception Not Handled” error can seem daunting at first, but it’s fixable with methodical steps. Whether caused by drivers, corrupt files, or misconfigured settings, solutions are readily available. Safe Mode, system tools, and proper updates resolve most cases. In persistent cases, reinstalling Windows or seeking help is necessary.
Preventing future issues starts with good habits: updating drivers, avoiding risky software, and maintaining backups. Use built-in tools like System Restore and antivirus protection wisely. When these precautions are followed, your system remains stable and efficient. Stay proactive, and you’ll rarely face this error again.