How to fix the vgk.sys blue screen (Vanguard BSOD)
Your PC blue-screened on Vanguard's driver, and if it is happening at startup you may be locked out of Windows right now. Both cases are fixable, your files are fine, start with your situation below.
By Neeraj Singh ~11 min Updated Jul 2026 85% found this helpful
Error message
Your PC ran into a problem and needs to restart. What failed: vgk.sys | Stop code: SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (vgk.sys)
Quick fix
Stuck in a blue screen loop before Windows even loads? Stop force-restarting into the same crash, repeated hard resets can damage files. Interrupt startup three times on purpose instead: power on, and the moment the Windows logo appears, hold the power button until the PC turns off. On the third start Windows opens its repair menu, go to Troubleshoot > Advanced options > Startup Settings > Restart, press 4 for Safe Mode and uninstall Riot Vanguard there. Method 1 walks you through it.
Blue screen while playing VALORANT or League? Your PC is not dying, Vanguard's driver is almost always colliding with something else at the deepest level of Windows. Update your graphics and chipset drivers, then fully exit tuning and overlay tools like MSI Afterburner before launching. Methods 2 and 3 cover it.
Intel 13th or 14th Gen CPU, or an overclocked PC? The recent wave of vgk.sys crashes on these systems is usually CPU instability showing up under Vanguard's heavy kernel work, not Vanguard misbehaving. Update the BIOS and load stable defaults, Method 5 steadies it.
Crashes survive everything? Reinstall Vanguard for a clean driver (Method 6), or let the crash file name the real culprit, Method 7 reads it with you.
✓ How to fix it
If you cannot reach your desktop, Method 1 is your way back in, do that first. Everyone else starts at Method 2 and works down. Each method tells you what success looks like so you know when to stop.
Method 1
Escape the boot loop: Safe Mode, then uninstall Vanguard
1Vanguard's driver loads while Windows starts, which is why the worst case crashes you before the desktop appears. Force the repair menu: power on, and when the Windows logo or spinning dots appear, hold the power button until the PC shuts off. Do this three times, and on the next start Windows shows Automatic Repair.
2Choose Troubleshoot > Advanced options > Startup Settings > Restart, then press 4 for Safe Mode or 5 for Safe Mode with Networking. Vanguard's driver does not run in Safe Mode, so the crashing stops here.
3In Safe Mode open Settings > Apps > Installed apps, uninstall Riot Vanguard and restart. Windows reaching the desktop again is your success sign. Now clear the underlying conflict with the methods below before a Riot game reinstalls Vanguard.
Figure 1: the escape route from the boot loop, step by step
Method 2
Update graphics and chipset drivers
1Stale low-level drivers are the most common thing vgk.sys collides with. Get the latest graphics driver from NVIDIA, AMD or Intel directly, and the chipset driver from your motherboard or laptop maker's support page for your exact model. Install pending Windows updates in the same sitting.
2Blue screens started right after a graphics driver update? Do a clean reinstall instead: run Display Driver Uninstaller (DDU) in Safe Mode, then install the fresh driver on the clean slate.
3Shut down fully and cold-start rather than restarting, so the kernel loads the new driver set from scratch. A full session of play with no crash is your confirmation.
Method 3
Fully exit overclocking, overlay and capture tools
1MSI Afterburner, RivaTuner, Intel XTU and overlay or capture software hook the same deep layer of Windows that Vanguard patrols, and the two colliding is a classic vgk.sys crash.
2Exit them completely from the system tray, minimised still means running. Glance at Task Manager afterwards, none of their processes should remain.
3Launch the game with a clean tray. Crashes gone? Re-add your tools one at a time to find the guilty one, then keep only that one closed while playing.
Method 4
Check antivirus and second anti-cheats
1Some third-party antivirus products and any second kernel anti-cheat from another game can clash with vgk.sys, two guards patrolling the same corridor.
2Temporarily disable the third-party antivirus, and uninstall anti-cheats left behind by games you no longer play, their drivers stay installed even after the game is gone.
3Test a session, then re-enable your protection. If the antivirus was the trigger, add exceptions for Vanguard and the game rather than leaving it off.
Method 5
Steady an unstable CPU: BIOS update and stock settings
1On Intel 13th and 14th Gen systems, aggressive motherboard voltage defaults have caused instability that shows up exactly under heavy kernel work like Vanguard's checks. Update your motherboard BIOS to a version carrying Intel's newer microcode, board makers shipped these specifically for this.
2Overclocked or running an aggressive XMP/EXPO memory profile on any CPU? Load stable or default settings in the BIOS and retest, an unstable tune crashes in the kernel long before it fails anywhere visible.
3Play a few sessions at stable settings. No more blue screens means the tune was the trigger, and you can re-apply it in smaller steps if you want the performance back.
Method 6
Reinstall Vanguard for a clean driver
1Try the gentle route first: open the Riot Client, click your profile icon, choose Settings > VALORANT > Repair and let it fix corrupt game files without a reinstall.
2Still crashing? Uninstall Riot Vanguard from Settings > Apps, restart, then launch VALORANT or League of Legends, both ship Vanguard, and it reinstalls a fresh vgk.sys and asks for one more restart so the driver can load at boot.
3If the uninstall itself fails or the crash returns instantly, do the full clean-out: open Command Prompt as administrator, run sc delete vgc and sc delete vgk, restart, delete the Riot Vanguard folder in C:\Program Files, then launch the game for a completely fresh install.
4You will know it worked when the game starts and a full session runs without a bugcheck. Still crashing with a brand new driver? The conflict lives outside Vanguard, Method 7 will name it.
Method 7
Read the minidump to name the real culprit
1Every blue screen writes a small crash file to C:\Windows\Minidump. It records which drivers were involved, so it can settle the whodunnit for you.
2Open the newest file with a free analyser such as Microsoft's WinDbg and run its automatic analysis. Read the module list around the crash.
3A third-party driver named alongside vgk.sys, a tuning tool, an old audio or network driver, another anti-cheat, is your prime suspect: update or remove it. Success is the next session running clean once that driver is dealt with.
One caution: if your PC also crashes outside Riot games, fails Windows updates or blue-screens on several different driver names, vgk.sys is a witness, not the culprit. Fix the wider Windows or hardware problem first, reinstalling Vanguard on a sick system just books the next crash.
Is Vanguard the cause or just the bystander?
This distinction saves you hours. vgk.sys runs at Ring 0, the deepest level of Windows, and it loads at boot on purpose, cheats try to load early, so Vanguard loads earlier. Living down there has a price: when anything else in kernel space misbehaves, a shaky graphics driver, a tuning tool's hook, an unstable CPU, the crash frequently lands on Vanguard's name because its driver was the one on duty. Your blue screen naming vgk.sys tells you where the crash happened, not always who caused it.
Figure 2: what collides with vgk.sys in kernel space
Common causes of the vgk.sys crash
Outdated graphics or chipset drivers colliding with Vanguard in kernel space.
Overclocking, overlay or capture tools keeping their hooks in while you play.
Third-party antivirus or a second kernel anti-cheat left over from another game.
CPU or memory instability, including affected Intel 13th and 14th Gen systems and aggressive XMP profiles.
Corrupted Vanguard driver files needing a clean reinstall.
A wider Windows or hardware fault where vgk.sys is only the name on the crash.
Expert insight
“The first thing I tell anyone with a vgk.sys boot loop is to stop hammering the restart button, three deliberate interrupts gets you a repair menu and Safe Mode, and Vanguard does not load there, so you are back in control in five minutes. After that it is detective work, not surgery: drivers first, then anything that pokes the kernel, Afterburner, XTU, overlays, actually closed, not in the tray. On the newer Intel builds I check BIOS and voltages before I blame Vanguard at all. And if the machine also crashes outside Riot games, I fix the PC first, the anti-cheat is just the messenger.”
Manager, Tech Support & Operations · 19+ years fixing Windows and system errors
Make sure this is the error you have
A few Vanguard problems look related but have their own guides. If VALORANT refuses to start with VAN9001 and a message about Secure Boot or TPM 2.0, that is a Windows 11 requirement check, not a crash, the VAN9001 guide enables it properly. A game that crashes to desktop or freezes without a blue screen is the crashing and freezes guide. And stutter or fan noise while playing without any crash belongs to the high CPU and stutter guide. If the game instead complains that Vanguard is not initialized without any blue screen, that is the vgc service, handled in the vgc not initialized guide. This page is only for the full blue screen, or the startup loop, that names vgk.sys.
Frequently asked questions
What is vgk.sys and is it safe?
It is Riot Vanguard's anti-cheat driver, installed with VALORANT and League of Legends. It is legitimate software, not malware, but it runs at the deepest level of Windows and loads at boot, so a fatal error in or around it crashes the whole PC instead of just the game.
How do I escape a vgk.sys boot loop?
Interrupt startup three times: power on, and when the Windows logo appears, hold the power button until the PC shuts off. On the next start Windows opens Automatic Repair. Choose Troubleshoot, Advanced options, Startup Settings, Restart, then press 4 for Safe Mode. Uninstall Riot Vanguard there and boot normally.
Does League of Legends use vgk.sys too?
Yes. Vanguard ships with both VALORANT and League of Legends, so either game installs the same vgk.sys driver, and launching either one after an uninstall will put it back. The fixes on this page apply whichever Riot game you play.
Why did vgk.sys start crashing my Intel 13th or 14th Gen PC?
Instability on some Intel 13th and 14th Gen CPUs, often from aggressive motherboard voltage defaults, surfaces as crashes under demanding kernel work like Vanguard's integrity checks. Update the BIOS to a version with Intel's newer microcode, load stable defaults and retest before blaming Vanguard alone.
Which tools should I close before playing?
Fully exit overclocking and tuning utilities such as MSI Afterburner and Intel XTU, plus overlay and capture software. Minimising them to the tray is not enough, they keep their hooks in the system. These tools poke the same kernel space Vanguard lives in and are common conflict partners.
Will reinstalling Vanguard fix the blue screen?
If Vanguard's own driver is corrupted, yes. Uninstall Riot Vanguard, restart, then launch VALORANT or League of Legends and it reinstalls a fresh vgk.sys. Do this after ruling out drivers, tools and CPU stability, because a reinstall cannot fix a conflict that lives outside Vanguard.
Can I disable Vanguard when I am not playing?
Yes. Exit Vanguard from its system tray icon when you are done playing. It stays inactive until the next boot it is asked to start with, and you will need to restart your PC before the next VALORANT or League session because the driver must load at startup.
How do I find which driver is really conflicting?
Read the minidump Windows writes on each blue screen, stored in C:\Windows\Minidump, with a free analyser such as WinDbg. The report lists the modules involved in the crash, and any third-party driver named alongside vgk.sys is your prime suspect to update or remove.
Still not working?
If the blue screens continue after every method including a clean minidump-guided driver fix, try a clean boot to catch a background app you have not suspected: run msconfig, hide Microsoft services, disable the rest along with startup items and retest. Some players also report conflicts with memory integrity, you can toggle it off under Windows Security > Core isolation to test, but switch it back on if it changes nothing, it protects you. Then test the hardware that fails quietly: run Windows Memory Diagnostic overnight and check the drive's health, because failing RAM or storage produces exactly this kind of random kernel crash. Browse the full set of Riot Vanguard error guides for anything adjacent, or submit your error to us with your minidump details for a tailored fix.
