Fix Windows Error 0x80040154 “Class Not Registered” – Causes, Solutions, and Expert Repair Tips

What Is Error 0x80040154 “Class Not Registered”?

Error 0x80040154 (“Class not registered”) appears when Windows cannot find or initialize a required COM (Component Object Model) class. In practice, this often means that a key DLL or component is unregistered, missing, or corrupted.

Depending on what is broken, you may see this error when:

• Running Windows Update, DISM、or SFC
• Launching specific apps or built-in features
• Trying to install or roll back updates

Common causes include:

• Required DLL/OCX files not registered correctly
• System files damaged by crashes, forced shutdowns, or malware
• Leftover changes after uninstalling security tools or tweaking the registry
• Mismatched architectures (32-bit vs 64-bit components)

The steps below focus on Windows 10 / Windows 11 and are ordered from easier to more advanced. Work through them in sequence and run all commands in an elevated (Administrator) Command Prompt.

① Reset Windows Update Components

If error 0x80040154 appears during Windows Update or when running DISM/SFC, start by resetting the Update components and cache.

1. Press Windows + X → click Windows Terminal (Admin) or Command Prompt (Admin).
2. Run the following commands one by one:

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old
net start wuauserv
net start cryptSvc
net start bits
net start msiserver

Why this helps: Windows Update keeps temporary files and catalogs in the SoftwareDistribution and catroot2 folders. If these become corrupted, COM-related update errors can appear. Renaming the folders forces Windows to recreate a clean cache.

② Re-register Core Windows Update DLLs (regsvr32)

Next, re-register key DLLs that Windows Update and COM rely on.

In the same elevated Command Prompt, run:

regsvr32 wuapi.dll
regsvr32 wuaueng.dll
regsvr32 msxml3.dll
regsvr32 wups.dll
regsvr32 wups2.dll
regsvr32 wuwebv.dll

Notes:

• If you are on a 64-bit system and see errors, you may also need to run regsvr32 from C:\Windows\SysWOW64 for 32-bit components.
• Each successful registration will display a confirmation dialog.

Why this helps: If these DLLs are not properly registered, Windows cannot access the COM classes they expose. Re-registering them restores the associations that Windows Update and related tools need to run.

③ Repair System Files with SFC and DISM

If COM or Update DLLs are damaged at the system level, simply re-registering them may not be enough. Use built-in repair tools:

In the elevated Command Prompt, run:

sfc /scannow
DISM /Online /Cleanup-Image /RestoreHealth

Let each command finish (it can take some time) and restart your PC afterwards.

Why this works: SFC scans and repairs protected system files, while DISM restores the integrity of the Windows image itself. If COM registrations fail because core system files are corrupted or missing, these tools often restore them automatically.

④ Check Required Services: Windows Modules Installer (TrustedInstaller)

Some update and servicing operations depend on specific Windows services being available—especially Windows Modules Installer (TrustedInstaller.exe).

1. Press Windows + R, type services.msc, and press Enter.
2. Find Windows Modules Installer in the list.
3. Make sure:

• Startup type is set to Manual or Automatic (not Disabled)
• The Status is Running when Windows Update is working

If it is disabled, set it back to Manual/Automatic, apply the changes, and then reboot.

Why this matters: If Windows cannot start critical services like TrustedInstaller, update-related COM operations may fail silently in the background and eventually surface as error 0x80040154.

⑤ Advanced: Use a Batch Script to Re-register Many DLLs at Once

For stubborn cases where only certain apps or components fail with “Class not registered,” power users sometimes use a batch script that re-registers a large number of system DLLs in one go.

Important: This step is more advanced and may take a long time. Only use scripts from trusted sources, and create a System Restore point or full backup before proceeding.

Typical process:

• Create a .bat file containing multiple regsvr32 commands for common system DLLs.
• Right-click the batch file → Run as administrator.
• Allow the script to complete, then restart Windows.

Why this can help: Instead of manually registering individual DLLs, a bulk script covers a much wider range of COM libraries, including components not directly related to Windows Update. This can resolve complex or long-standing 0x80040154 issues where it is unclear which specific class is failing.

⑥ Perform an In-Place Repair Upgrade (or Clean Install)

If none of the previous steps work and 0x80040154 keeps returning, your Windows installation may be deeply corrupted.

At this point, consider an in-place repair upgrade:

1. Download the official Windows 10/11 installation media (ISO or Setup tool) from Microsoft.
2. Run Setup.exe from within Windows.
3. Choose Keep personal files and apps when prompted.

This process reinstalls the core OS while preserving your files, installed apps, and most settings.

If even that fails—or you want a completely fresh start—you can back up your data and perform a clean install.

Why this helps: A repair install rebuilds system files, COM registrations, and registry structures from clean installation media. Persistent “Class not registered” errors caused by deeply tangled corruption are often resolved only by this level of repair.

Additional Tips & Troubleshooting Tricks

• Temporarily disable third-party antivirus or security suites.
  Some tools hook into COM and update processes and can block registrations or updates. Use Windows Security alone during troubleshooting and re-enable third-party tools afterwards.
• Use Safe Mode or WinRE for offline repairs.
  If SFC/DISM or updates cannot run in normal mode, boot into Safe Mode or the Windows Recovery Environment and run: sfc /scannow DISM /Image:C:\ /Cleanup-Image /RestoreHealth (Adjust the drive letter if Windows is installed on another partition.)
• Check for architecture mismatches.
  If a 32-bit DLL is being used from a 64-bit process (or vice versa), COM activation can fail. For legacy apps, ensure they are built for the correct platform (x86 vs x64) and register DLLs using the matching version of regsvr32:
  • C:\Windows\System32\regsvr32.exe → 64-bit
  • C:\Windows\SysWOW64\regsvr32.exe → 32-bit

Summary Table

Final Thoughts

Error 0x80040154 (“Class not registered”) is a sign that something is seriously wrong with how Windows is loading COM components—it is not a harmless cosmetic message. The good news is that in most cases, you can fix it by working through the steps above in order: reset services and cache, re-register DLLs, repair system files, and—if necessary—perform an in-place repair.

If you still see “Class not registered” after following these methods, note exactly which app or operation triggers the error and check the Event Viewer for details. That extra information can help narrow down which specific component is failing.

COM-related problems can be frustrating, but they are usually solvable with patience and systematic troubleshooting.

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タグ: DLL registration, Windows error, SFC DISM repair, Windows Update Failure, In-Place Upgrade, 0x80040154, Class not registered, COM error, regsvr32 fix, system corruption