Cause #1: Buggy or Outdated Graphics Driver
The culprit here is almost always a graphics driver (NVIDIA, AMD, Intel) that tried to suspend a thread right as it was ending. I've seen this constantly with driver versions rolled out too fast — NVIDIA 470.x through 510.x were notorious for this. The OS detects the race condition and throws 0xC000004B to stop a system hang.
How to Fix It
- Boot into Safe Mode (hold Shift while restarting, choose Troubleshoot → Advanced Options → Startup Settings → Enable Safe Mode).
- Download Display Driver Uninstaller (DDU) — don't bother with Windows Device Manager removal, it leaves junk.
- Run DDU in Safe Mode, choose "Clean and restart" for your GPU vendor.
- Install the latest stable driver from your GPU maker's site. Skip beta or Game Ready drivers if you're not gaming — Studio drivers (NVIDIA) or Pro drivers (AMD) are more stable.
If the error popped right after a driver update, roll back to the previous version instead. Go to Device Manager, right-click your GPU, Properties → Driver → Roll Back Driver.
Cause #2: Antivirus or Security Software Interfering
Third-party antivirus (McAfee, Norton, even some AVG builds) sometimes inject hooks into system threads to monitor process creation. When a thread is terminating and the AV tries to intercept it, bang — 0xC000004B. Windows Defender rarely has this problem. I've lost count of how many times uninstalling Norton fixed this on client machines.
How to Fix It
- Uninstall the antivirus completely using the vendor's removal tool (not just the Programs list). Most have one on their site.
- Reboot and see if the error stops. If it does, switch to Windows Defender — it's good enough for 99% of users.
- If you need third-party AV, install the latest version and make sure it's updated. Old builds cause this.
Cause #3: Corrupt System Files or Bad Windows Update
Sometimes a Windows update (I'm looking at you, KB5021233 from early 2023) mangles a kernel-level thread management file. Or a corrupt system file like ntoskrnl.exe causes the same race condition. This is less common than the first two causes, but I've seen it on machines that had sudden power loss during an update.
How to Fix It
- Open Command Prompt as Administrator.
- Run
sfc /scannow— it'll take 15-20 minutes. If it finds corrupt files, reboot and run it again. - Then run
DISM /Online /Cleanup-Image /RestoreHealth— this fixes the image that sfc uses. - If the error started after a specific update, uninstall it. Go to Settings → Update & Security → Windows Update → Update History → Uninstall Updates. Pick the one that matches the error's first appearance date.
Quick-Reference Summary Table
| Cause | Likelihood | Fix | Tools Needed |
|---|---|---|---|
| Buggy graphics driver | High (60%) | DDU + reinstall stable driver | DDU, GPU vendor driver installer |
| Antivirus interference | Medium (25%) | Uninstall AV, use removal tool | AV vendor removal tool |
| Corrupt system files or bad update | Low (15%) | sfc /scannow, DISM, uninstall update | Command Prompt |
If none of these fix it, you're probably looking at a hardware fault — bad RAM or failing SSD. Run a memory test (Windows Memory Diagnostic) and check the drive with CrystalDiskInfo. But 9 times out of 10, it's the graphics driver. Start there.