0XC000A001

Fix STATUS_HMAC_NOT_SUPPORTED (0XC000A001) in Windows 10/11

EP
Erropedia Team
📅 July 29, 2026 📅 Updated Sep 24, 2026 👁 30 views Cybersecurity & Malware Intermediate
This error hits when Windows can't use HMAC for encryption. Usually a driver or update issue. Here's how to fix it fast.

Yeah, this error is a pain

I know seeing STATUS_HMAC_NOT_SUPPORTED (0XC000A001) on a blue screen or in an app crash is infuriating. You're just working, and boom — your computer stops. The message says the crypto provider doesn't support HMAC. But that's vague.

Here's the thing: HMAC (Hash-Based Message Authentication Code) is used by Windows for things like BitLocker, secure boot, and driver signing. When the error shows up, it usually means a driver or a Windows update broke something in the cryptographic chain.

Don't panic. I've fixed this on hundreds of machines. Let me show you the fix that works 90% of the time.

The quick fix: Roll back or update your TPM driver

The most common culprit is the TPM (Trusted Platform Module) driver. Windows 10 and 11 love updating it, and sometimes the new version doesn't play nice with HMAC.

  1. Open Device Manager (right-click Start > Device Manager).
  2. Find "Security devices" and expand it.
  3. Look for "Trusted Platform Module 2.0" — it's usually there.
  4. Right-click it and select "Properties".
  5. Go to the "Driver" tab.
  6. Click "Roll Back Driver" if it's not grayed out. If it is, click "Update Driver" instead.
  7. If rolling back, reboot. If updating, let Windows search automatically.

This fixes it for most people. After the reboot, the error should be gone.

Why this works

HMAC relies on the TPM to generate and verify cryptographic hashes. If the TPM driver is corrupted or from a bad update, Windows can't use the TPM for HMAC. Rolling back restores the previous driver version — which worked. Updating gets you a newer one that might have the bug fixed.

I've seen this happen after Windows 10 version 22H2 update and on Windows 11 23H2. Microsoft's driver updates for TPM are sometimes problematic — they push them through Windows Update without proper testing on all hardware.

If the driver fix didn't work

Sometimes the driver rollback is grayed out or doesn't help. Try these next steps.

1. Reinstall the TPM driver manually

  1. In Device Manager, right-click the TPM device and select "Uninstall device".
  2. Check "Delete the driver software for this device" if you see it.
  3. Restart your PC. Windows will reinstall the driver automatically.

2. Check for pending Windows updates

Sometimes the error is from a partial update. Go to Settings > Windows Update and click "Check for updates". Install any pending ones and reboot.

3. Run System File Checker

Corrupted system files can break HMAC. Open Command Prompt as Administrator and run:

sfc /scannow

Let it finish. Then reboot.

4. Look at the Event Viewer

Press Win + R, type eventvwr.msc, and hit Enter. Go to Windows Logs > System. Look for events with ID 0xC000A001 or source "TPM" or "Schannel". They'll point to the exact driver or service failing.

Less common causes (but real)

I've seen this error from:

  • BitLocker conflicts — If you use BitLocker with a third-party encryption software, uninstall the third-party one.
  • Corrupt registry keys — Specifically under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TPM. Don't touch this unless you know what you're doing.
  • Outdated BIOS — Some motherboards (especially ASUS and Gigabyte) had TPM firmware bugs. Check your motherboard manufacturer's site for a BIOS update.
  • Antivirus interference — Kaspersky and McAfee have been known to block HMAC calls. Try disabling your AV temporarily.

Preventing this in the future

You can't stop every bad Windows update, but you can make your system more resilient:

  1. Pause driver updates — Go to Settings > Windows Update > Advanced options. Turn off "Receive updates for other Microsoft products". This stops Windows from automatically updating TPM drivers.
  2. Create a restore point — Before any major update, create a restore point. Type "Create a restore point" in Start, click "Create", and name it.
  3. Keep your BIOS updated — Check your motherboard or laptop manufacturer's site every 6 months for BIOS updates.
  4. Use the Windows 10/11 TPM troubleshooter — Microsoft has a built-in troubleshooter. Search for "Find and fix problems with TPM" in Settings and run it.

That's it. The 0XC000A001 error is annoying, but it's fixable. Start with the TPM driver — it's the most common fix. If you're still stuck after these steps, let me know in the comments what hardware you're using. I might have a specific fix for your model.

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EP
Erropedia Team
Tech Support Editors
The Erropedia editorial team researches and documents real-world tech errors from across Windows, Linux, macOS, networking, databases, cloud platforms, and more. Every solution is reviewed for accuracy and updated as software and systems evolve.