"Class not registered" error is usually caused by incorrect registration of COM objects. Solutions include: 1. Run the program as an administrator; 2. Use regsvr32 to re-register the relevant DLL or OCX files, such as scrrun.dll, msxml3.dll, etc.; 3. If it is an Office-related problem, select to repair Microsoft Office online through the control panel; 4. Ensure that the 32-bit or 64-bit DLL is registered with the corresponding version of regsvr32. The 32-bit DLL should use C:\Windows\SysWOW64\regsvr32.exe; 5. Uninstall and reinstall the problematic software to ensure that the components are registered correctly; 6. Run sfc /scannow and DISM /Online /Cleanup-Image in the administrator command prompt. /RestoreHealth repairs system files; 7. View application logs through event viewer and locate the specific missing class ID (CLSID); 8. If the error occurs in the browser, enable ActiveX control support, but only for trusted sites. Troubleshooting in this order usually solves the problem.

The "Class not registered" error in Windows 10 usually appears when an application tries to access a COM (Component Object Model) object or ActiveX control that isn't properly registered in the system. This commonly happens with older software, Office applications, web browsers using ActiveX, or tools relying on specific DLLs.

Here's how to fix it:

1. Run the App as Administrator

Sometimes, the issue is due to insufficient permissions.

• Right-click the application or shortcut.
• Select "Run as administrator" .
• If it works, set it permanently:
  • Right-click → Properties → Compatibility tab → Check "Run this program as an administrator" .

2. Re-register the Problematic DLL or OCX File

The missing or corrupted class might be tied to a specific file. You'll need to re-register it using regsvr32 .

Steps:

1. Press Win X → Choose Command Prompt (Admin) or Windows Terminal (Admin) .
2. Type the following command (replace filename.dll with the actual file if known):

 regsvr32 filename.dll

If you don't know the file, common culprits include:

• scrrun.dll (Scripting Runtime)
• msxml3.dll , msxml6.dll (XML support)
• jscript.dll
• vbscript.dll
• ole32.dll
• actxprxy.dll

Example:

 regsvr32 scrrun.dll

? You should see a "DllRegisterServer in [file] succeeded" message.

?? If you get an error, the file might be missing or corrupted.

3. Repair Microsoft Office (If Error is Office-Related)

This error is frequently in Outlook, Excel, or Word when add-ins fail.

Try this:

• Go to Control Panel → Programs → Programs and Features .
• Select Microsoft Office → Click Change → Choose Repair .
• Use Online Repair (not Quick Repair) for best results.

After repair, restart your PC.

4. Check 32-bit vs 64-bit Compatibility

Windows has separate registries for 32-bit and 64-bit COM classes.

• If you're using a 32-bit app on 64-bit Windows , it looks in Wow6432Node .
• A mismatch can cause "Class not registered".

Fix:

• Make sure you're registering the correct version of the DLL.
• Use the 32-bit version of regsvr32 for 32-bit DLLs:
  • C:\Windows\SysWOW64\regsvr32.exe (for 32-bit)
  • C:\Windows\System32\regsvr32.exe (for 64-bit)

So, to register a 32-bit DLL:

 C:\Windows\SysWOW64\regsvr32.exe filename.dll

5. Reinstall the Problematic Software

If the app causing the error isn't part of Windows or Office:

• Uninstall it completely.
• Download the latest version from the official site.
• Reinstall it (preferably as admin).

This ensures all COM components are registered correctly during setup.

6. Scan for System File Corruption

Corrupted system files can break COM registration.

Run these commands in an elevated Command Prompt :

 sfc /scannow

After it finishes, run:

 DISM /Online /Cleanup-Image /RestoreHealth

Restart your PC after both complete.

7. Check Event Viewer for Clues

To identify the exact missing class:

• Press Win X → Event Viewer .
• Go to Windows Logs → Application .
• Look for Error entries around the time the crash happened.
• The details may show something like:

  "Class not registered: {XXXXXXXX-XXXX-XXXX-XXXXXXXXXXXXXX}"

You can search online for that CLSID to identify the missing component.

8. Enable ActiveX in Browser (If Web-Based)

If the error occurs in Internet Explorer or a legacy web app:

• Open Internet Options → Security tab.
• Select Internet zone → Click Custom Level .
• Scroll down to ActiveX controls and plug-ins .
• Enable:
  • Run ActiveX controls and plug-ins
  • Script ActiveX controls marked safe

?? Only do this on trusted sites.

Summary Checklist:

• ? Run as administrator
• ? Re-register relevant DLLs using regsvr32
• ? Repair or reinstall the affected software (especially Office)
• ? Use correct 32/64-bit regsvr32 version
• ? Run sfc /scannow and DISM
• ? Check Event Viewer for the missing class ID
• ? Reinstall the app if nothing works

Most "Class not registered" errors are fixed by re-registering the right component or repairing the software. The key is identifying which class or app is failing — once you know that, the solution is usually straightforward.

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