Introduction
The Windows stop code SYSTEM_THREAD_EXCEPTION_NOT_HANDLED is a Blue Screen of Death (BSOD) that appears when a system thread throws an exception that the Windows kernel fails to catch. You’ll typically see “Stop code: SYSTEM_THREAD_EXCEPTION_NOT_HANDLED” along with a file name like nvlddmkm.sys, dxgmms2.sys, rtwlane.sys, or another driver. It can happen randomly, on startup, during gaming, after a driver or Windows update, or when plugging in new hardware. While startling, this BSOD is usually fixable.
This guide goes beyond generic advice. You’ll get a complete, step-by-step troubleshooting path to identify exactly which driver broke, analyze minidumps, and replace or roll back the faulty component. By the end, you’ll know how to stabilize your system and prevent the error from returning.
Understanding the Error
The SYSTEM_THREAD_EXCEPTION_NOT_HANDLED bug check (code 0x0000007E or 0x7E, sometimes 0x1000007E) means a kernel-mode thread raised an exception (for example, access violation or invalid operation) that wasn’t handled. In plain language: a driver or low-level system component did something unexpected, and Windows couldn’t recover safely, so it stopped to protect your data.
Common scenarios that trigger this Windows 10/11 BSOD:
- A buggy, outdated, or incompatible driver (graphics, storage, Wi‑Fi, audio, chipset, USB).
- GPU driver issues after a major update, game install, or overclock.
- Corrupted system files or Windows component store problems.
- Disk/SSD problems (bad sectors, failing NVMe firmware).
- RAM instability (defective memory, unstable XMP/overclock).
- BIOS/UEFI conflicts or outdated firmware.
- Third-party antivirus or endpoint drivers hooking kernel/network.
- Malware or rootkits (less common, but possible).
Why it’s critical to fix: continued crashes risk data loss, filesystem corruption, and hardware wear. The right sequence of diagnostics will pinpoint the failing module and restore stability.
Common Causes
Skimmable overview of the most likely culprits behind a SYSTEM_THREAD_EXCEPTION_NOT_HANDLED BSOD:
- Graphics drivers: NVIDIA (nvlddmkm.sys), AMD (atikmpag.sys, amdkmdag.sys), Intel (igdkmd64.sys)
- Display subsystem: dxgmms2.sys, dxgkrnl.sys
- Network/Wi‑Fi: Realtek (rt640x64.sys, rtwlane.sys), Intel (Netwtwxx.sys), Broadcom (bcmwl63a.sys)
- Audio: Realtek (rtkvhd64.sys), Creative, or third-party audio processing
- Storage/RAID: Intel RST (iaStorA.sys, iaStorAVC.sys), older AHCI/NVMe drivers, storport.sys
- USB and chipset drivers: OEM USB 3.x controllers and filter drivers
- Antivirus/security: Kernel filters (e.g., klif.sys, aswSP.sys, mbam.sys)
- System files: ntfs.sys, fltmgr.sys (often secondary; upstream third-party driver is at fault)
- RAM/disk issues: Hardware instability causing drivers to fail
- BIOS/UEFI settings: Aggressive XMP/EXPO, CPU overclocks, outdated BIOS
- Windows updates: Newly introduced incompatibilities
- Malware: Rare but can masquerade as drivers
Common driver files you may see:
| Driver file (.sys) | Likely Component | Notes |
|---|---|---|
| nvlddmkm.sys | NVIDIA GPU | Common after GPU update; use DDU + clean reinstall |
| atikmpag.sys / amdkmdag.sys | AMD GPU | Similar symptoms; try previous WHQL release |
| igdkmd64.sys | Intel GPU | Update from Intel or OEM |
| dxgmms2.sys / dxgkrnl.sys | DirectX/Display | Often indicates GPU stack issue |
| rt640x64.sys / rtwlane.sys | Realtek NIC/Wi‑Fi | Update or roll back |
| bcmwl63a.sys | Broadcom Wi‑Fi | Update from OEM |
| iaStorA.sys / iaStorAVC.sys | Intel RST | Consider switching to Microsoft Standard AHCI |
| rtkvhd64.sys | Realtek Audio | Update or revert |
| klif.sys / aswSP.sys | Security suite | Temporarily uninstall security software |
Preliminary Checks
Before deep diagnostics, perform these foundational steps.
- Boot into Safe Mode (with or without Networking)
- If Windows loads: Settings > System > Recovery > Advanced startup > Restart now > Troubleshoot > Advanced options > Startup Settings > Restart > Press 4 (Safe Mode) or 5 (Safe Mode with Networking).
- If stuck in a BSOD loop: Interrupt boot 3 times to invoke Windows Recovery Environment (WinRE), then follow the same path (Troubleshoot > Advanced options > Startup Settings).
- Alternative: Hold Shift while clicking Restart on the login screen.
- Back up important data
- Copy critical files to an external drive or cloud while in Safe Mode.
- Consider creating a System Restore point or a full system image if you can boot normally.
- Run basic health checks
- Open an elevated Command Prompt (Admin) and run:
sfc /scannow
If SFC reports unrepairable files, run:
DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow
- Check disk health (will schedule at reboot if needed):
chkdsk C: /f /r
If you cannot boot Windows, run SFC and DISM offline from WinRE (adjust drive letters as needed):
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows
DISM /Image:C:\ /Cleanup-Image /RestoreHealth
Step-by-Step Troubleshooting
Follow these steps in order, from easiest to most targeted. The goal is to identify which driver broke and replace, roll back, or remove it.
- Undo recent changes
- If the BSOD started after a driver update, Windows update, or new hardware: uninstall or disconnect the change to test.
- In Safe Mode: Device Manager > right-click the device > Properties > Driver > Roll Back Driver (if available).
- Settings > Windows Update > Update history > Uninstall updates.
- Cleanly reinstall display (GPU) drivers
- GPU drivers are a top cause of SYSTEM_THREAD_EXCEPTION_NOT_HANDLED.
- Use DDU (Display Driver Uninstaller) in Safe Mode:
- Download from the official site; disconnect the internet to prevent automatic driver installs.
- Run DDU > select GPU vendor > Clean and restart.
- Install the latest WHQL driver from NVIDIA/AMD/Intel, or try a stable previous version if the latest is problematic.
- Optional: During install, choose Clean installation and disable GeForce Experience/Extras to minimize conflicts.
- Update chipset, storage, and network drivers from the OEM
- Go to your PC or motherboard manufacturer support page (Dell, HP, Lenovo, ASUS, MSI, etc.).
- Install latest Chipset, ME/PSP, SATA/AHCI/NVMe, Intel RST (or remove it), LAN/Wi‑Fi, and Audio drivers.
- Avoid generic drivers from random sites. When in doubt, prefer the OEM-provided packages.
- Remove or replace third-party antivirus/security drivers
- Temporarily uninstall any third-party antivirus, endpoint protection, VPN, or network filter drivers.
- Use the vendor’s clean removal tool (e.g., for Kaspersky, Avast, etc.).
- Reboot and test. If stable, either reinstall the latest version or switch to Microsoft Defender.
- Disable overclocks and test stock settings
- In BIOS/UEFI:
- Disable XMP/EXPO and any CPU/GPU overclocks.
- Load Optimized Defaults.
- In Windows, ensure GPU overclock utilities are closed/uninstalled and return to defaults.
- Check memory and storage stability
- Run Windows Memory Diagnostic (Win+R > mdsched.exe > Restart now and check).
- For deeper testing, use MemTest86 (USB boot) for at least 4 passes.
- Check SSD/NVMe firmware using the vendor tool (Samsung Magician, Crucial Storage Executive, Intel Memory and Storage Tool). Update firmware if recommended.
- Analyze minidumps to identify the exact driver
How to enable and find minidump files
- Ensure Small memory dump (256 KB) is enabled:
- Control Panel > System > Advanced system settings > Startup and Recovery > Settings > Write debugging information: Small memory dump.
- Minidumps are stored in: C:\Windows\Minidump
- If Minidump is empty, ensure the system drive has space and that crash dumps aren’t disabled in registry or by optimization tools.
Use BlueScreenView (easiest)
- Download BlueScreenView (NirSoft), run it, and open C:\Windows\Minidump.
- Look at the “Bug Check String” (SYSTEM_THREAD_EXCEPTION_NOT_HANDLED) and the “Caused By Driver” column.
- Note the driver file (e.g., nvlddmkm.sys, rtwlane.sys, iaStorA.sys).
Use WinDbg (deeper analysis)
- Install WinDbg (Preview) from the Microsoft Store.
- File > Start debugging > Open dump file > choose the latest .dmp in C:\Windows\Minidump
- In the command pane, run:
.symfix
.reload
!analyze -v
- Look for:
- “Probably caused by”: the suspected driver/module.
- ExceptionCode and stack traces pointing at a third-party .sys file.
- To inspect a specific module:
lmvm drivername
(Replace drivername with the module from !analyze, e.g., nvlddmkm)
If the dump implicates a Microsoft core file (like ntoskrnl.exe), scroll the stack for third-party drivers or run:
!thread
!irpfind
- Replace or roll back the faulty driver
If you identified a driver (example: rtwlane.sys for Realtek Wi‑Fi):
- Device Manager > Network adapters > Realtek Wireless > Properties > Driver > Roll Back if available.
- Or uninstall the device, tick “Delete the driver software for this device,” reboot, and install the latest known-good driver from the OEM.
- For stubborn drivers, list and remove with PnPUtil:
pnputil /enum-drivers
Find the matching oem##.inf for the faulty driver, then:
pnputil /delete-driver oem##.inf /uninstall /force
- Reboot and install the correct driver package.
GPU example (nvlddmkm.sys):
- Run DDU in Safe Mode.
- Install a different branch (e.g., prior WHQL), turn off experimental features, and test.
Storage example (iaStorA.sys):
- If using Intel RST, try the latest OEM build. If problems persist and you’re not using RAID:
- Switch to Microsoft Standard AHCI Controller:
- Device Manager > IDE ATA/ATAPI controllers > Intel SATA/RAID > Update driver > Browse > Let me pick > Standard AHCI Controller > Restart.
- Ensure BIOS SATA mode matches (AHCI vs RAID). Changing BIOS mode improperly can prevent boot—back up first.
- Switch to Microsoft Standard AHCI Controller:
- Rebuild system files and component store
- If dumps vary or implicate core Windows files:
- Repeat:
DISM /Online /Cleanup-Image /RestoreHealth
sfc /scannow
- If corruption persists, proceed to System Restore or an in-place repair.
- Apply BIOS/UEFI and firmware updates
- Update BIOS/UEFI to the latest stable release.
- Update SSD/NVMe firmware via vendor tools.
- After update, load Optimized Defaults, then re-apply only necessary settings.
- Use System Restore or uninstall problematic updates
- WinRE > Troubleshoot > System Restore > select a restore point before the first BSOD.
- Windows Update > Uninstall updates if a specific KB is implicated.
- In-place repair upgrade (keeps files and apps)
- Download the latest Windows 10/11 ISO from Microsoft.
- Run setup.exe from within Windows and choose Keep personal files and apps.
- This refreshes system files and drivers without wiping data.
- Clean boot to isolate conflicts
- Run msconfig > Services tab > Hide all Microsoft services > Disable all.
- Startup tab > Open Task Manager > Disable all startup items.
- Reboot and test. Re-enable items in batches to find the conflicting component.
- Last resort: clean install
- If crashes persist after all of the above, back up data and perform a clean installation of Windows. Install drivers from the OEM in a controlled sequence, testing stability after each major driver.
Advanced Diagnostics
When standard steps don’t isolate the cause, use these expert tools carefully.
Driver Verifier (advanced)
- Purpose: stress-test and monitor drivers to force failing ones to reveal themselves (often producing a different BSOD like DRIVER_VERIFIER_DETECTED_VIOLATION).
- Warning: Driver Verifier can cause intentional BSODs. Create a restore point and ensure you know how to boot into Safe Mode or WinRE.
- Enable:
- Run Command Prompt (Admin):
verifier /standard /all
- Reboot and use the system normally until a crash occurs.
- After a crash, analyze the new dump with !analyze -v to identify the failing driver.
- Disable:
verifier /reset
- If you get stuck in a boot loop: boot into Safe Mode and run the reset command.
Event Viewer
- Open Event Viewer (eventvwr.msc) > Windows Logs > System.
- Look for events around the time of crash: “BugCheck”, disk warnings, or driver initialization failures.
- Use these clues to align with driver timestamps and updates.
Driver and device inventory
- List loaded drivers:
driverquery /v /fo table
- Identify unsigned drivers: run sigverif and review results.
- Correlate driver versions and dates with recent changes.
When to Seek Professional Help
Consider professional repair or hardware replacement if:
- MemTest86 reports persistent memory errors (replace RAM).
- SMART/firmware tools report SSD/HDD failures (replace the drive).
- The BSOD persists across clean Windows install with minimal drivers.
- You see signs of motherboard, PSU, or GPU instability (random shutdowns, power issues, artifacts).
- You manage mission-critical systems and need guaranteed root-cause analysis and data protection.
Document everything you’ve tried and bring recent minidumps and Event Viewer logs—this saves time and cost.
Prevention Tips
Keep BSODs like stop code SYSTEM_THREAD_EXCEPTION_NOT_HANDLED from returning with these best practices:
- Maintain driver hygiene:
- Prefer OEM drivers and WHQL releases.
- Avoid beta drivers on production systems.
- Don’t stack multiple vendor utilities that hook the same subsystem (e.g., multiple RGB or fan controllers).
- Update Windows routinely, but pause or defer feature updates on mission-critical machines until vetted.
- Keep BIOS/UEFI and device firmware current.
- Avoid aggressive overclocks on daily-use machines; if you overclock, validate thoroughly.
- Create periodic System Restore points and full backups (image your OS drive).
- Use a single, reputable security suite or rely on Microsoft Defender.
- Monitor disk health with vendor tools and replace aging drives before failure.
- After major changes (GPU swap, new RAM), stress test for stability before regular use.
Conclusion
The stop code SYSTEM_THREAD_EXCEPTION_NOT_HANDLED almost always traces back to a misbehaving driver or underlying hardware instability. By starting with Safe Mode, backing up data, running SFC/DISM/CHKDSK, and then moving into minidump analysis with tools like BlueScreenView or WinDbg, you can identify the exact driver at fault. Replace or roll back the culprit, update chipset/storage/network components from your OEM, disable overclocks, and update BIOS/firmware. If needed, leverage Driver Verifier, System Restore, or an in-place repair.
Most BSODs are fixable with a careful, methodical approach. Take it step by step—you’ve got this.
FAQ
Can I ignore a SYSTEM_THREAD_EXCEPTION_NOT_HANDLED BSOD if it only happens once?
A single, isolated crash could be a fluke, but it’s best to run quick checks: SFC, DISM, and ensure drivers—especially GPU and chipset—are current. If it happens again, follow the full troubleshooting process.
Does this stop code mean my hardware is failing?
Not necessarily. It’s more often a driver or software issue. However, if you see recurring crashes after clean driver installs and OS repair, test RAM (MemTest86) and check SSD/HDD health and firmware. Persistent failures can indicate hardware problems.
The BSOD shows no driver name—how do I find the culprit?
Enable minidumps and analyze with BlueScreenView or WinDbg. Use !analyze -v to find “Probably caused by” and inspect the stack. Consider Driver Verifier if dumps aren’t conclusive.
Is it safe to use Driver Verifier?
Yes, but with caution. Driver Verifier stresses drivers and may trigger more BSODs to reveal the issue. Create a restore point, know how to enter Safe Mode, and disable it with verifier /reset if you hit a loop.
How do I replace a broken driver cleanly?
- Uninstall the device in Device Manager, check “Delete the driver software for this device,” and reboot.
- For stubborn cases, use PnPUtil to remove the matching oem##.inf:
pnputil /enum-drivers
pnputil /delete-driver oem##.inf /uninstall /force
- Install the correct, OEM-provided or latest WHQL driver and test stability.
