Fix STATUS_FLT_INVALID_CONTEXT_REGISTRATION (0xC01C0017)
This error means a filter driver registered with bad parameters. Usually from corrupted antivirus or backup software. Reinstall the filter driver or clean its registration.
Quick answer for advanced users
Run fltmc unload <problematic-driver> then fltmc load <driver> in an admin command prompt. If that fails, delete the driver's registry key under HKLM\SYSTEM\CurrentControlSet\Services and reinstall the app.
What's really happening here
You're seeing STATUS_FLT_INVALID_CONTEXT_REGISTRATION (0xC01C0017) because the Filter Manager—a core part of Windows that manages file system filter drivers—rejected a registration request. A filter driver (like the one from your antivirus, backup software, or encryption tool) tried to attach itself to a volume or the file system stack with an invalid context structure. I've seen this most often after an antivirus update goes sideways or when a backup app like Acronis or Veeam gets partially uninstalled. One client had it happen because their security software's filter driver was still loaded after they'd already removed the program. The filter manager doesn't care about your intentions—it just sees bad data.
How to fix it step by step
- Identify the offending driver
Open an elevated Command Prompt (right-click, Run as Administrator) and type:
fltmc instances
Look for any driver with a status ofStoppedorFailed. Common culprits:sftredir(Symantec),snapman(Acronis),bfsflt(BlueStacks), orFileCrypt(BitLocker). - Unload the bad filter driver
fltmc unload <driver-name>
Replace<driver-name>with the actual name from step 1. If you get "The specified driver could not be unloaded" it means another process holds a reference—reboot into Safe Mode and try again. - Reload it clean (or remove it permanently)
If the driver belongs to software you still use, load it fresh:
fltmc load <driver-name>
If it's from uninstalled software, don't reload—just delete its registry key under:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\<driver-name>
Alternative fix if the main one fails
When fltmc refuses to cooperate—like the driver is marked as boot-start and won't unload—you'll need to disable it in the registry. Go to HKLM\SYSTEM\CurrentControlSet\Services, find the driver's key, and set its Start value to 4 (Disabled). Reboot into Safe Mode if needed. I had a case where a corrupt antivirus driver required booting into Safe Mode with Networking to download a removal tool. Also, run sfc /scannow after—some filter drivers corrupt system files when they crash.
Preventing it from coming back
Don't stack multiple security products with real-time file scanning. Each one installs its own filter driver, and they fight over context registrations. Stick to one antivirus. When uninstalling backup or security software, use the vendor's official uninstaller—not just the Programs menu. For example, Acronis True Image has a cleanup utility you can download from their site. Also, avoid installing software like BlueStacks or Dropbox on systems that already run heavy filter stacks (encryption + antivirus). The filter manager is fragile—treat it gently.
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