You plug in your external drive and get that cryptic "Invalid Class Name" error in Device Manager. Frustrating, but the fix is straightforward and usually takes about two minutes.
The Fix: Delete the UpperFilters Registry Key
- Press Win + R, type
regedit, hit Enter. - Navigate to:
This GUID is the class for disk drives.HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e967-e325-11ce-bfc1-08002be10318} - In the right pane, look for a value named UpperFilters. Right-click it and delete it. If there's also LowerFilters, delete that too.
- Close Regedit, restart your PC.
- Open Device Manager, right-click the problem drive, select "Scan for hardware changes". The drive should now appear without the error.
That's it. No driver reinstall needed, no diskpart commands.
Why This Works
What's actually happening here is that a filter driver — often from a DVD burning tool like CloneCD, Daemon Tools, or an old antivirus — has corrupted the registry entry for the disk class. Windows uses the UpperFilters and LowerFilters values to load additional drivers on top of or below the standard disk driver. When a filter driver is uninstalled improperly, these registry values point to a class name that no longer exists. The result: Windows can't instantiate the device, and you get "Invalid Class Name".
The reason step 3 works is that deleting the orphaned filter values forces Windows to fall back to the default disk driver with no extra layers. It's like removing a burnt-out bulb in a series circuit — the rest of the lights come back on. The drive itself is fine; the software layers above it are broken.
Less Common Variations
Error on a Specific Partition (Not the Entire Drive)
If the error shows only for one partition, check HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{71a27cdd-812a-11d0-bec7-08002be2092f} — that's the volume class. Delete UpperFilters or LowerFilters there. This happens after installing certain USB-to-SATA bridge drivers.
Error Persists After Deletion
If the drive still has the error, the filter driver itself might be stuck in the system. Use driverquery /v > drivers.txt to list all drivers, then look for anything with "filter" in the name. Uninstall the associated software. One real-world case: Norton Ghost left a filter that no modern Windows version supports. Removing it fixed the class name error.
Error on an Internal NVMe Drive
NVMe drives use class GUID {4d36e97b-e325-11ce-bfc1-08002be10318}. Same fix — delete the UpperFilters/LowerFilters values. This can happen after installing or removing Intel RST drivers. I've seen it on Windows 11 22H2 after an RST update failed.
Registry Key Doesn't Exist
If the key under Control\Class is missing entirely, create it manually. Right-click the Class key, select New > Key, name it with the correct GUID. Then create a string value named Class with data DiskDrive (for disk drives). This is rare but happens on heavily corrupted installs — often after an incomplete Windows update.
Prevention
- Uninstall software properly. Use the official uninstaller, not brute-force deletion. Filter drivers are notorious for leaving registry leftovers. Programs like Daemon Tools, Alcohol 120%, and older versions of Nero are common culprits.
- Create a system restore point before installing any software that adds filter drivers. Search for "restore point" in Start, create one. If the class name error appears, roll back.
- Avoid registry cleaners. They sometimes delete valid entries while leaving the filter values intact, making things worse. Stick to manual edits with Regedit.
- On Windows 10 and 11, check the driver store with
pnputil /enum-driversperiodically. If you see orphaned filter drivers, remove them withpnputil /delete-driverand the matching .inf file name.
That's the whole story. No fluff, no "ensure you have backups" warning — just the fix and the reasoning behind it. The registry edit is safe if you follow the steps exactly. If you're still stuck, the error is almost always a leftover filter driver, not a dying drive.