STATUS_INVALID_SIGNATURE (0XC000A000) Fix Guide

What Is STATUS_INVALID_SIGNATURE (0xC000A000)?

This error pops up when Windows tries to load a driver, DLL, or boot file that either lacks a valid digital signature or has one that's been corrupted. You'll see it as a blue screen (BSOD) or a boot loop after a driver update, a Windows update, or sometimes after malware scrubbed a signature. The culprit here is almost always a third-party driver that wasn't signed properly.

I've seen this most often on Windows 10 and 11 machines after someone installed a printer driver or a GPU driver from a random manufacturer site. The fix is straightforward once you know which cause you're dealing with.

Cause #1: Unsigned or Corrupt Third-Party Driver

This is the most common trigger. A driver you installed recently — typically for a network card, GPU, or printer — doesn't pass signature validation. Windows 10 and 11 enforce driver signing by default. If the driver's signature got corrupted during download or was never signed, you get this error.

How to Fix It

1. Boot into Safe Mode. Restart your PC and spam F8 or Shift + Restart to get to Advanced Startup. Select Troubleshoot > Advanced Options > Startup Settings > Enable Safe Mode with Networking.
2. Open Device Manager. Right-click the Start button and select Device Manager.
3. Look for yellow triangles next to devices. That's your tell. Right-click the device, go to Properties, then Driver Details. If you see "No digital signature" or "Invalid signature," that's the one.
4. Uninstall the driver. Right-click the device and choose Uninstall device. Check "Delete the driver software for this device" if prompted.
5. Reboot normally. Windows will install a generic driver. If the error doesn't return, you found the problem. Get a signed driver from the manufacturer's official site.

Pro tip: Don't bother with driver rollback here — the driver was never valid. Just wipe it and start fresh.

Cause #2: Corrupted System Files

Sometimes the signature error isn't about a new driver. It's about Windows system files themselves getting corrupted. A bad Windows update, a dying hard drive, or a sudden power loss can corrupt the signature on ntoskrnl.exe or winload.exe. This causes the error on boot before Windows even loads.

How to Fix It

1. Boot from a Windows installation USB. You'll need a USB drive with Windows 10 or 11 setup. If you don't have one, create it on another PC using the Media Creation Tool.
2. Open Command Prompt. On the setup screen, press Shift + F10. That gets you a command line.
3. Run SFC offline. Type this and hit Enter:
   

   sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

   Replace C: with your system drive letter if it's different. SFC will scan and replace corrupted system files.

4. If SFC fails, run DISM:
   

   DISM /Image:C:\ /Cleanup-Image /RestoreHealth

5. Reboot. Remove the USB and start normally. If the error's gone, you're done.

If SFC or DISM can't fix it, you've got a deeper issue — likely a failing SSD or malware. Move to Cause #3.

Cause #3: Malware That Tampered with Signatures

This one's nasty. Some rootkits and bootkits — like variants of the Alureon or TDL4 families — specifically target signed drivers. They either replace a legit driver with their own unsigned version or modify the signature database to load their payload. You'll see the 0xC000A000 error at boot because Windows detects the tampering.

How to Fix It

1. Run a boot-time antivirus scan. Use Microsoft Defender Offline or a tool like Kaspersky Rescue Disk. Create a bootable USB on another machine, boot from it, and run a full scan. This catches what normal scanning misses.
2. Check the boot configuration. In Command Prompt from the recovery environment, type:
   

   bcdedit /enum

   Look for any entries that point to files outside the Windows folder (like on a hidden partition). If you see something suspicious — like a path to a random folder — that's malware.

3. Force a signature recheck. If malware damaged the signature cache, rebuild it:
   

   del %SystemRoot%\System32\catroot2\*.* /q
   regsvr32 /s /i shell32.dll

   Then reboot.

4. As a last resort, do a clean install. If you're still getting the error after scanning and rebuilding, nuke it. Pull your data first via a recovery environment.

Quick-Reference Summary Table

If none of these fix it, you're looking at hardware failure — run a full disk check and replace the drive if needed. That's the end of the road for software fixes.