How to Fix Windows 11 Update Blocked by cFosSpeed Driver

If a Windows 11 feature update stalls at 30–40% and the installer reports that a “cFosSpeed driver is incompatible” or that “cFosSpeed is blocking the Windows 11 update,” the problem is almost always an out‑of‑date kernel‑level network filter left on the system. The fix is straightforward but must be performed carefully: update to a Windows‑11‑compatible cFosSpeed package (or remove all traces of the driver), clear any leftover driver packages from the driver store, and then re‑attempt the upgrade. This article walks through five proven methods—with verified commands, OEM‑specific notes, and safety checks—so you can finish your Windows 11 upgrade without losing network functionality or destabilizing the system.

Background / Overview​

cFosSpeed is a packet‑shaping/network‑traffic‑prioritization driver that many motherboard vendors bundle as part of their utility suites. It installs a kernel‑mode filter driver (commonly named cfosspeed6.sys or cfosspeed.sys) that hooks into the network stack and can therefore be flagged by Microsoft’s upgrade safeguards if it is incompatible with newer kernel expectations. cFosSpeed has historically been bundled with major OEM utilities for gaming motherboards and laptops.
Microsoft proactively blocks known problematic or vulnerable drivers during feature updates and via the Vulnerable Driver Blocklist (and related partner offer‑block mechanisms). That behavior protects users from drivers that could cause a blue screen, break networking, or introduce security issues after an upgrade. The blocklist and upgrade‑hold mechanisms are the reason Windows will stop an upgrade if it detects an unsupported third‑party driver operating at kernel level.
In practice the fix is one of the following, in order of least invasive to most: update cFosSpeed to a version that the vendor certifies for Windows 11; fully uninstall cFosSpeed; remove leftover driver packages from the driver store; temporarily disable the cFosSpeed service; or perform the upgrade using alternate Microsoft tools after ensuring the driver is removed. Community reports show users succeed after installing a current trial binary from the vendor, or after thoroughly removing residual driver files and packages.

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Quick checklist (try these first)​

• Create a system restore point and back up critical files before changing drivers.
• Ensure you have an Administrator account for driver operations.
• Temporarily disable third‑party antivirus or endpoint protection during driver removal.
• Restart after every major step (uninstall, driver store cleanup, reinstall).
• If an OEM utility (Armoury Crate, Dragon Center, APP Center) auto‑installs drivers, disable its auto‑update features or uninstall that utility first. Community reports show OEM suites can reinstall cFosSpeed automatically.

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What you need to verify before changing anything​

• Confirm the problematic driver name shown by the Windows installer—often cfosspeed6.sys or cfosspeed.sys.
• Check Device Manager → Network adapters and Properties → Details → Driver File or INF name for any cFosSpeed references.
• Note whether cFosSpeed came from an OEM bundle (ASUS, MSI, Gigabyte, ASRock) or a direct cFos/cFosSpeed installation. OEM bundles often install branded versions (Turbo LAN, Gaming LAN Manager, XFast LAN).

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Method 1 — Update cFosSpeed to a Windows‑11‑compatible release (fastest / preferred)​

When available, the least risky option is to install an updated cFosSpeed build that explicitly supports Windows 11. cFosSpeed binaries are now distributed from Atlas Tech Solutions (the current vendor/portal), and the official download pages list version numbers and build dates.

• Why this works: the updated driver replaces the legacy kernel filter with a version that no longer triggers the Windows upgrade safeguard.
• What to do (step‑by‑step):
• Download the current cFosSpeed trial or installer from the vendor’s download page. The vendor pages list builds such as v13.01 build 3001 and later test builds; newer trial builds (for example v13.10 build 3004) are also listed on the official download portal.
• Uninstall your current cFosSpeed via Settings → Apps → Installed apps (or Programs and Features) and restart the PC.
• Install the downloaded build (the trial is sufficient to clear the upgrade block).
• Reboot again, then retry the Windows 11 feature update.

Notes and cautions:

• Some OEM versions are license‑tied or co‑branded; reinstalling the trial may show a “restore license” or “trial” prompt—this is normal and will not prevent the update.
• If the vendor site does not explicitly state a fix for the exact Windows 11 feature update you’re applying, treat the claim cautiously and prefer removal if in doubt.

If updating succeeds, keep the driver if you need traffic shaping; otherwise uninstall it after the upgrade.

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Method 2 — Completely uninstall cFosSpeed (recommended if you don’t need it)​

If you don’t depend on cFosSpeed, a complete removal is often the simplest path. Windows 11’s networking stack and QoS do a good job for typical users.
Common uninstall approaches:

• Standard Settings uninstall
• Settings (Win+I) → Apps → Installed apps → search “cFosSpeed” → Uninstall → follow prompts and check “Remove driver” if presented. Restart.
• Programs and Features (classic)
• Win+R → appwiz.cpl → locate cFosSpeed → Uninstall. Some OEM installers are only visible here.
• PowerShell force removal (for stubborn packages)
• Open PowerShell as Administrator and try these (these attempt package removal if present):
• Get-Package -Name "cFosSpeed" | Uninstall-Package -Force
• Get-AppxPackage -Name "cFosSpeed" | Remove-AppxPackage
• Use Win32 product enumeration with caution: Get-WmiObject -Class Win32Product | Where-Object {$.Name -like "cFosSpeed"} | ForEach-Object {$_.Uninstall()}
• Network properties uninstall
• Win+R → ncpa.cpl → Right‑click your active adapter → Properties → Look for “cFosSpeed … (NDIS 6)” → Uninstall → OK.

After uninstall, reboot. If Windows Update still blocks the upgrade, leftover driver package(s) in the driver store are almost certainly present—move to Method 3.
Practical tip: OEM suites can reinstall the driver on boot or after an update. If you use ASUS Armoury Crate, MSI Dragon Center, or Gigabyte APP Center, disable or remove the OEM utility first. Community reports show these suites re‑push cFosSpeed automatically.

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Method 3 — Manual removal of leftover driver packages (driver store & registry cleanup)​

Even after uninstallers run, Windows may keep the driver package in the driver store (C:\Windows\System32\DriverStore\FileRepository) and Windows Update can detect it. Use PnPUtil and registry cleanup to remove lingering pieces. These are elevated operations—create a restore point before proceeding.
Why use PnPUtil? It safely enumerates third‑party driver packages and removes them from the driver store. Microsoft documents the /enum‑drivers and /delete‑driver switches and the /uninstall /force flags. Use them exactly as shown.
Step‑by‑step

• Create a restore point first:
• Start → type “restore point” → Create a restore point → Create → name it “Before cFosSpeed removal”.
• Enumerate third‑party drivers:
• Open Command Prompt as Administrator and run:
• pnputil /enum‑drivers
• Search the output for references to cFos, cfosspeed, cfosspeed6.sys, or the OEM INF (oem*.inf). Note the published INF name (for example oem42.inf).
• Remove the driver package from the driver store:
• pnputil /delete‑driver oem42.inf /uninstall /force
• Replace oem42.inf with the actual INF you found. The /uninstall flag removes the driver from any device using it; /force helps when the driver is in use. Microsoft documents the syntax and flags.
• Manually delete driver files (only after pnputil removal):
• Delete these common locations if they exist:
• C:\Windows\System32\drivers\cfosspeed6.sys
• C:\Windows\System32\drivers\cfosspeed.sys
• C:\Windows\System32\DriverStore\FileRepositorycfosspeed
• C:\Program Files\cFosSpeed
• C:\Program Files (x86)\cFosSpeed
• C:\ProgramData\cFos
• If a file reports “access denied,” boot to Safe Mode and try again.
• Registry cleanup (advanced; proceed with caution)
• Win+R → regedit → locate and remove these keys only if they reference your cFos installation:
• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cFosSpeed
• HKEY_LOCAL_MACHINE\SOFTWARE\cFos
• HKEY_LOCAL_MACHINE\SOFTWARE\Atlas Tech Solutions
• HKEY_CURRENT_USER\SOFTWARE\cFos
• HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\cFos
• Do not delete keys you’re not certain about; a restore point is essential.
• Clean the driver cache and check system health:
• Run these elevated commands:
• dism /online /cleanup‑image /startcomponentcleanup
• sfc /scannow
• dism /online /cleanup‑image /restorehealth
• Reboot and re‑attempt the Windows 11 upgrade.

If the Windows installer still reports the driver, re‑run pnputil to confirm no cFos entries remain: pnputil /enum‑drivers | findstr /i "cfos" and driverquery | findstr /i "cfos" to verify. File and community troubleshooting guides recommend this step to ensure full removal before retrying the update.

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Method 4 — Temporarily disable the cFosSpeed service (useful when leaving software installed)​

If you want to keep the software installed but prevent it interfering with the installer, try disabling its service. This method is mixed in effectiveness because Windows Update may check for the presence of driver files rather than service state, but it’s safe to try first.

• Steps:
• Win+R → services.msc → find cFosSpeed Service → Right‑click → Properties.
• Set Startup type = Disabled and click Stop.
• Apply → OK → Restart the PC.
• Retry the Windows 11 update.
• Alternative: msconfig route
• Win+R → msconfig → Services tab → uncheck cFosSpeed → Apply → Restart.

If the update succeeds, re‑enable the service afterward (reverse the steps). If the update still blocks, do the complete removal steps (Methods 2–3).

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Method 5 — Alternate install paths (Installation Assistant / Media Creation / Clean install)​

If all driver removal attempts fail or you need to proceed quickly, Microsoft’s Installation Assistant or the Media Creation Tool can often bypass some Windows Update pipeline checks. These are valid fallback options:

• Windows 11 Installation Assistant — performs an in‑place upgrade and may succeed when Windows Update stalls.
• Media Creation Tool / ISO — create install media and run setup.exe from the mounted ISO to perform an in‑place upgrade (choose “keep files and apps”).
• Clean install — last resort; guarantees a clean driver set but requires backing up data and reinstalling apps.

Community and support threads note that the Installation Assistant or in‑place upgrade via ISO often succeeds where the Windows Update path did not, but you should still remove the driver beforehand if possible to avoid post‑upgrade problems.

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OEM‑specific notes (ASUS, MSI, Gigabyte, ASRock)​

• ASUS:
• cFosSpeed is commonly bundled as part of Turbo LAN or Armoury Crate for ROG/TUF motherboards. Use Armoury Crate’s uninstall or update workflows where available—some users report Armoury Crate uninstalls cFos more thoroughly than Windows uninstall. If Armoury Crate re‑installs cFosSpeed, disable its auto‑update feature.
• MSI:
• MSI bundles cFosSpeed in Dragon Center / Gaming LAN Manager. Uninstall both Gaming LAN Manager and cFosSpeed; look in C:\Program Files (x86)\MSI\Dragon Center\LanManager for uninstaller executables (unins001.exe). Disable Dragon Center updates to prevent reinstallation.
• Gigabyte:
• Gigabyte ships rebranded traffic shaping tools or includes cFosSpeed in APP Center. If you don’t need the OEM tools, remove APP Center and any “Gigabyte Speed” components. Gigabyte sometimes provides a standalone cFosSpeed remover. Check your support downloads.
• ASRock (XFast LAN):
• ASRock’s XFast LAN was a rebrand of cFosSpeed. If you see XFast entries, treat them identical to cFosSpeed—uninstall and remove leftovers.

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Verification & troubleshooting checklist (after any removal attempt)​

• Verify no cFosSpeed drivers remain:
• pnputil /enum‑drivers | findstr /i "cfos"
• driverquery | findstr /i "cfos"
• Run Windows Update readiness checks:
• Settings → Windows Update → Check for updates. If the Update UI offers a “Fix issues” link, follow it for explicit guidance.
• Check Event Viewer:
• Win+X → Event Viewer → Windows Logs → System. Look for driver or service errors referencing cFosSpeed or cfosspeed6.sys.
• If Windows Update still refuses to proceed, collect the SetupDiag log (Microsoft’s SetupDiag) or run an in‑place upgrade using the Media Creation Tool as a fallback. Community threads recommend using the Installation Assistant or MCT when the standard path fails.

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Why Microsoft blocks drivers and why you should be cautious​

Microsoft balances security/stability and compatibility: blocking outdated kernel drivers avoids catastrophic failures after an upgrade (BSODs, networking loss, data corruption). The Vulnerable Driver Blocklist and partner‑requested upgrade hold mechanisms exist to prevent large numbers of devices from receiving an update that will break hardware or critical workloads. For this reason, don’t attempt to bypass the check by simply suppressing warnings; fix the driver or remove it safely.

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Common user outcomes and community guidance​

• Many users report success by installing a current trial version from the cFos/Atlas download pages, rebooting, then running the Windows update again. The trial installer replaces older kernel hooks so the upgrade can continue. That approach is widely reported in community threads, but treat it as a temporary, pragmatic workaround rather than a permanent solution if you don’t want the traffic shaper.
• If cFosSpeed keeps reappearing after removal, check and remove the OEM manager or disable its auto‑update. Persistent re‑installs almost always come from an OEM suite.

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Quick reference: verified commands and steps​

• Enumerate third‑party drivers:
• pnputil /enum‑drivers
• (Microsoft documentation confirms the command syntax and behavior.)
• Remove a driver package found in the driver store:
• pnputil /delete‑driver oemXX.inf /uninstall /force
• Replace oemXX.inf with the INF name found in step 1.
• Clean image and system files:
• dism /online /cleanup‑image /startcomponentcleanup
• sfc /scannow
• dism /online /cleanup‑image /restorehealth
• Reset network stack (after driver removal if network issues appear):
• netsh winsock reset
• netsh int ip reset
• ipconfig /flushdns
• netcfg -d
• Clear Windows Update cache (if update metadata seems corrupted):
• net stop wuauserv
• net stop bits
• Rename C:\Windows\SoftwareDistribution → SoftwareDistribution.old
• Rename C:\Windows\System32\catroot2 → catroot2.old
• net start wuauserv
• net start bits
• (These steps are standard Windows Update maintenance steps and are recommended when update downloads or metadata are corrupted.)

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Risks, caveats, and final warnings​

• Removing driver packages can break hardware/functionality if you remove the wrong driver. Always confirm the INF name and provider before deleting and create a restore point. Microsoft explicitly warns that blocking drivers can cause devices or software to malfunction, and removal should be done carefully.
• Registry edits are inherently risky. Only delete cFos‑related keys you recognize; otherwise, restore from the restore point.
• If your device is managed by corporate IT or has endpoint protection, consult the IT team before making driver changes.
• If you rely on the OEM utility for other essential features (fan control, RGB, firmware updates), uninstalling the entire OEM suite may remove those conveniences—plan accordingly.

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Conclusion — recommended sequence​

• Backup and create a restore point immediately.
• Try the simple path: update cFosSpeed to the latest vendor build (trial is sufficient). Reboot and retry the Windows 11 upgrade.
• If that fails, uninstall cFosSpeed via Settings/Programs and reboot.
• If the upgrade still blocks, run pnputil and remove any cFosSpeed INF entries from the driver store, then delete residual files and perform DISM/SFC. Verify no driver remains.
• If required, disable OEM utilities that might re‑install the driver, or use the Windows 11 Installation Assistant / Media Creation Tool to perform the upgrade after confirming the driver is absent.

Fixing a cFosSpeed driver blocking a Windows 11 update is a routine, fixable condition when approached methodically: prefer updating first, then removal and driver‑store cleanup if necessary. Microsoft’s upgrade safeguards are doing their job by protecting your system—work with them, don’t around them, and you’ll complete the upgrade with minimal disruption.

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Source: H2S Media 5 Methods to Fix cFosSpeed Driver Blocking Windows 11 Update or Installation