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System Thread Exception Not Handled: BSOD Fixes

January 7, 2026 No comments yet

Few things bring a computer session to a screeching halt like the notorious Blue Screen of Death (BSOD). Among the various cryptic error messages users encounter, one particularly stubborn one is “System Thread Exception Not Handled.” You might see it with a dreaded automatic restart on your Windows machine, sometimes with a file name like nvlddmkm.sys or atikmpag.sys, referring to graphics drivers. What causes it, and more importantly, how can you fix it?

TL;DR

The “System Thread Exception Not Handled” BSOD typically indicates a problem with out-of-date or corrupted drivers, especially graphics and system drivers. This error often appears during boot-up, making it tricky to diagnose. To fix it, updating or reinstalling drivers, restoring the system, and checking windows files usually resolves the problem. In rare cases, hardware issues may also cause this error.

What Does “System Thread Exception Not Handled” Mean?

This BSOD error means a system thread generated an exception that the error handler didn’t catch — essentially, a low-level process blew up and couldn’t be managed. It usually points to:

  • Driver issues (most commonly graphic drivers)
  • Corrupted or incompatible system files
  • BIOS or hardware conflicts
  • Overclocking instability

More often than not, the error includes a specific file name, helping point to what caused the crash. For example:

  • nvlddmkm.sys — NVIDIA graphics drivers
  • atikmpag.sys — AMD graphics drivers
  • dxgmms2.sys — DirectX graphics kernel

The key to solving this issue lies in identifying the problematic component and resolving it through updates, repairs, or replacements.

Common Fixes for “System Thread Exception Not Handled”

Try these methods in the order listed below, from simplest to more advanced. Always back up important data before making system changes.

1. Boot into Safe Mode

If your system is stuck in a BSOD loop during startup, your first step is to boot into Safe Mode:

  1. Shut down the PC and turn it back on.
  2. Once Windows starts loading, press and hold the power button to interrupt.
  3. Repeat this 2-3 times until Windows boot options appear.
  4. Go to Advanced Options > Startup Settings and select Enable Safe Mode with Networking.

Safe Mode loads the system with minimal drivers, allowing troubleshooting without triggering the BSOD.

2. Update or Roll Back Drivers

Drivers are often the root cause, especially after a system update or hardware change. In Safe Mode or normal Windows, open Device Manager:

  1. Right-click the Start button and choose Device Manager.
  2. Expand the category linked to the error (usually Display Adapters).
  3. Right-click your GPU and choose Update driver or Properties > Driver > Roll Back Driver.

Still having issues? Completely uninstall and reinstall the driver:

  1. Use a utility like DDU (Display Driver Uninstaller) to remove GPU drivers cleanly.
  2. Download the latest version directly from the manufacturer’s website (e.g., NVIDIA, AMD, or Intel).
  3. Reboot and install the new driver.

3. Run System File Checker (SFC) and DISM

Corrupted Windows system files? These commands help clean things up:

  1. Open Command Prompt as administrator.
  2. Type: sfc /scannow and press Enter.
  3. After completion, run these in order:
    • DISM /Online /Cleanup-Image /CheckHealth
    • DISM /Online /Cleanup-Image /ScanHealth
    • DISM /Online /Cleanup-Image /RestoreHealth

These tools check for corrupted or missing system files and try to repair them automatically.

4. Check for Windows Updates

Incorrect or missing system updates can also destabilize thread handling:

  1. Open Settings > Windows Update.
  2. Click Check for updates.
  3. Install everything available, including optional updates, and restart.

Also check for optional driver updates by clicking Advanced options > Optional updates.

5. Disable Hardware Acceleration (Temporarily)

Some users report the error vanishing after disabling hardware acceleration in browsers or system apps. While it’s a workaround more than a fix, it helps if the issue is GPU-related.

To disable in Chrome, for example:

  1. Go to Settings > System.
  2. Turn off Use hardware acceleration when available.
  3. Restart the browser.

6. Restore or Reset Your System

If all else fails, a restoration might be needed:

  • System Restore: Roll back to an earlier point using Restore Points.
  • Reset this PC: Go to Settings > Recovery and choose to reset with your files preserved (or removed for a fresh start).

FAQs and Special Cases

Why Does the Error Keep Coming Back?

Frequent returns usually indicate either:

  • You haven’t fully removed the problematic driver.
  • There’s hardware damage, often RAM, GPU, or overheating.

Can Overclocking Cause It?

Yes. GPU, CPU, or RAM overclocking can cause instability, resulting in the error. Try resetting BIOS or UEFI settings to default:

  1. Restart your PC and enter the BIOS/UEFI menu (usually Del or F2).
  2. Find the option to restore default/reset components to factory settings.
  3. Save and exit.

How Do I Find Which Driver Caused It?

Use the built-in Event Viewer:

  1. Search and open Event Viewer.
  2. Navigate to Windows Logs > System.
  3. Look for entries labeled with errors, especially right before the crash time.

Alternatively, tools like WhoCrashed or BlueScreenView can analyze crash dumps and show the driver that failed.

Prevention Tips for the Future

Here are a few strategies to reduce the risk of ever seeing this BSOD again:

  • Keep drivers updated — Use manufacturer sources, not just Windows Update.
  • Install OS updates regularly — Don’t delay important Windows security and stability updates.
  • Avoid installing unknown or beta drivers unless necessary.
  • Perform periodic hardware checks — Overheating or degraded RAM can prompt BSODs.

Wrapping Up

The “System Thread Exception Not Handled” BSOD may seem complicated, but it usually boils down to outdated or corrupted drivers. Most users can fix it by updating or reinstalling drivers, repairing system files, or returning to a previous system state. If you’ve tried the steps above and the issue persists, it may be time to consider a deeper investigation into system hardware.

Be proactive: maintain a clean, driver-updated system and use monitoring tools to catch issues before they escalate to BSOD territory. Your future self (and your computer) will thank you.