Fix STATUS_FLT_NO_DEVICE_OBJECT 0XC01C0019 on Backup or Mount

What the Error Means

You see STATUS_FLT_NO_DEVICE_OBJECT (0xC01C0019) when a program tries to talk to a volume and the underlying storage device isn't there. It's not a corrupted drive — the data is usually fine. The problem is that Windows lost the pointer between the volume letter and the actual hardware device object. This happens most often after:

• You changed a drive letter while a backup tool (like Veeam or Windows Server Backup) was running.
• You tried to run Sdelete or Diskpart Clean on a drive that was briefly disconnected or sleeping.
• You have a leftover or misconfigured storage filter driver from an old antivirus or encryption tool.

The real fix depends on why the pointer got dropped. Let's walk through it from easiest to hardest.

30-Second Fix: Reassign the Drive Letter

Half the time, the volume is fine — the letter just got orphaned. Disk Management can see it, but nothing else can. Here's what to do:

1. Press Win + R, type diskmgmt.msc, and hit Enter.
2. Find the volume that throws the 0xC01C0019 error. It'll likely show as healthy but with no drive letter, or with a weird letter like E: that you don't use.
3. Right-click the volume and pick Change Drive Letter and Paths.
4. If it already has a letter, click Remove. Confirm the warning. After you remove it, the volume will disappear from File Explorer — that's normal.
5. Now click Add, choose Assign the following drive letter, pick a letter (use one you haven't used before, like X:), and click OK.
6. Wait 5 seconds. The volume should reappear in File Explorer.
7. Run your backup or Sdelete command again. If the error's gone, you're done.

If the volume doesn't show up in Disk Management at all, or if reassigning the letter doesn't work, move to the next step.

5-Minute Fix: Clear Stale Filter Drivers with Regedit

This error often traces back to a corrupted filter driver entry in the registry. Windows maintains a stack of mini-filters that sit between the file system and the hardware. One bad entry can break the device object link for every volume. The most common culprit is an old antivirus or encryption driver that didn't uninstall cleanly.

Before you start: back up your registry. Seriously. In Regedit, go to File > Export, save a copy somewhere.

1. Open Regedit (search for it in the Start menu, or press Win + R, type regedit, hit Enter).
2. Navigate to:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{71a27cdd-812a-11d0-bec7-08002be2092f}

3. In the right pane, look for a key called UpperFilters or LowerFilters. If it exists, double-click it.
4. You'll see a multi-string list of filter driver names. Look for anything that doesn't belong — leftovers from an old program you uninstalled, or a duplicate entry. Common troublemakers: partmgr duplicates, any driver with snapman (from old Acronis), or dmboot.
5. If you're not sure what's safe, take a screenshot. Then remove everything from the list EXCEPT partmgr. Yes, delete the others. After you click OK, the registry will update immediately.
6. If there is no UpperFilters or LowerFilters key at all, don't add one — that's a good sign.
7. Restart your computer.
8. After reboot, test your command again. If the error is gone, you're set. If not, proceed to the advanced fix.

Note: I've seen this fix work on Windows 10 22H2 and Windows Server 2019 after a failed Trend Micro uninstall left a dangling filter. It's worth trying even if you don't remember installing any storage software.

15+ Minute Fix: Use Diskpart to Clean and Rebuild the Volume

If the first two steps didn't work, the volume's partition table or metadata is corrupted enough that the device object can't be rebuilt. This usually happens after a power loss during a format or a failed partition resize. The data is still there, but Windows can't reattach the volume. You'll need to clean the disk and recreate the partition.

Warning: This destroys all data on that disk. If you have anything important, stop here and try data recovery software first (I've had good luck with DMDE free version — it can extract files without fixing the volume).

1. Open Command Prompt as Administrator (right-click Start, choose Command Prompt (Admin) or Terminal (Admin)).
2. Type diskpart and press Enter. You'll see the DISKPART prompt.
3. Type list disk and press Enter. Make note of the disk number that has the problem volume. Do NOT guess — check the size.
4. Type select disk X (replace X with the correct number). Confirm with detail disk.
5. Type clean and press Enter. After this command finishes, the disk will be completely empty. It takes 1-2 seconds.
6. Type create partition primary and press Enter.
7. Type format fs=ntfs quick and press Enter. Wait for it to finish (usually under a minute).
8. Type assign letter=Z (or any letter you want).
9. Type exit to leave Diskpart.
10. Close the Command Prompt.
11. Check in File Explorer — the drive should appear with the letter you chose.
12. Run your original command. The 0xC01C0019 error should be gone.

If you still get the error after a clean wipe, the disk hardware itself is failing. Run a CHKDSK from the Command Prompt: chkdsk Z: /f (replace Z with your drive letter). Swap out the disk if you see bad sectors.

One More Thing: Check if It's a Temporary Glitch

Sometimes this error is transient — especially if you're running Sdelete on a USB 3.0 drive that goes to sleep. Go to Control Panel > Power Options > Change plan settings > Change advanced power settings, look for USB settings > USB selective suspend setting, and set it to Disabled. Then unplug and replug the drive. That's often the fastest fix for external drives.