explorer.exe “Class not registered” in Windows 11 and 10: how to fix it

What the message means

“Class not registered” is a COM error (code 0x80040154). Explorer, the Start menu, Settings and many built-in apps open each other through registered components. When one of those registrations is missing or damaged, the request fails and Windows shows this message with explorer.exe in the title bar.

Microsoft doesn’t publish a single fix for it. Answers on Microsoft Q&A, including some from Microsoft support staff, point to corrupt system files, a damaged per-user registration (for example the handler that opens folders or file:// links), and problems that began after an update or a power cut. The fixes below follow that order, from the safest to the most drastic.

First, get a working desktop

1. Press Ctrl + Shift + Esc to open Task Manager.
2. On the Processes page, right-click Windows Explorer and choose Restart.
3. If the taskbar doesn’t come back, select Run new task (in Windows 10 it’s under the File menu), type explorer.exe and press Enter.

Task Manager’s Run new task box is also the easiest way to start Command Prompt or PowerShell when the Start menu won’t open. Tick Create this task with administrative privileges only when a step below says to run as administrator.

Match the fix to where the error appears

Where you see it	Start with
Clicking Start, the taskbar or search	Fix 1, then Fix 2
Opening photos or other files	Fix 3
Clicking links, or in Microsoft Edge	Fix 4
Settings won’t open	Fix 1, then the ms-settings guide
Everywhere, only in one account	Fix 5

Fix 1: Repair Windows system files

Microsoft’s instructions run DISM first, so SFC has a healthy component store to copy from. Open Command Prompt as administrator and run:

DISM.exe /Online /Cleanup-image /Restorehealth
sfc /scannow

Restart when both finish. Our sfc /scannow guide explains what each result message means. If the PC lost power before the error started, check the drive too with chkdsk C: /f and let it scan at the next restart.

Fix 2: Re-register the Start menu

If the error appears when you click Start or the taskbar, re-register the Start menu package. Microsoft’s Start menu troubleshooting page gives this command for Windows 11 and recent Windows 10 versions. Open Windows PowerShell without administrator rights and run:

Add-AppxPackage -Path "C:\Windows\SystemApps\Microsoft.Windows.StartMenuExperienceHost_cw5n1h2txyewy\AppxManifest.xml" -Register -DisableDevelopmentMode

The non-admin part matters. Microsoft notes that running Add-AppxPackage from an elevated window registers the app for the administrator account instead of yours. Sign out and back in afterwards. If the Start menu itself crashes or stays blank, ShellExperienceHost.exe problems are a close relative of this one.

Fix 3: Reset default apps and re-register Photos

When the message appears as you open a picture or another file, the file association is the usual suspect, often after an update.

1. Open Settings > Apps > Default apps.
2. Type the file type, such as .jpg, in the search box and pick Photos or another viewer you trust.
3. On recent Windows 11 builds you can also scroll down and use Reset all default apps; Windows 10 calls it Reset to the Microsoft recommended defaults.

If Photos itself shows the error, re-register it from a normal PowerShell window, using the pattern from Microsoft’s Store apps troubleshooting guide:

Get-AppxPackage *Microsoft.Windows.Photos* | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

Fix 4: When links or Edge show the error

A Microsoft moderator on Q&A describes this version as a breakdown in the hand-off between the browser and the Windows shell. To check, press Win + R and open the same folder or network path directly. If that works, the shell is fine and the browser side needs attention:

• Install all updates in Settings > Windows Update, including any Microsoft Edge WebView2 update.
• Go to Settings > Apps > Installed apps, find Microsoft Edge, choose Modify and then Repair.
• Set your browser again under Settings > Apps > Default apps.

Fix 5: Test a new user account

Add a second local account in Settings > Accounts > Other users (Family and other users on Windows 10), sign in to it and try the same action. If the error doesn’t appear there, your own profile is damaged. Move your files to the new account; our guide to deleting a user profile properly covers removing the old one once everything is copied.

Fix 6: Rule out startup programs

Users have traced the error to Start menu replacements, shell themes, security tools and iCloud. Run msconfig, open the Services tab, tick Hide all Microsoft services, select Disable all, then disable startup apps from Task Manager and restart. If the error is gone, turn things back on in small groups to find the cause.

Fix 7: Undo a recent update or repair Windows

If it started after an update, remove that update in Settings > Windows Update > Update history > Uninstall updates, or use System Restore if you have a restore point. When Windows won’t reach the desktop, interrupt start-up three times to open the recovery environment and choose Troubleshoot > Advanced options.

As a last step, Microsoft support staff suggest an in-place repair: run setup from Windows installation media of the same version and choose to keep your files and apps. It reinstalls Windows without wiping your data, but back up first.

Fixes to avoid

• Downloading ExplorerFrame.dll or other system files from DLL download sites. SFC and DISM restore genuine copies from Microsoft.
• Re-registering every DLL in a folder with a regsvr32 loop. It can register files that were never meant to be, and it won’t repair damaged ones.
• Changing DCOM permissions in Component Services without a backup. No Microsoft guidance links that to this error.

If File Explorer crashes outright rather than showing this message, see Explorer crashes on right-click, and if taskbar icons have vanished, see taskbar icons missing.

Related guides

• How to run sfc /scannow in Windows 11 and 10 (and read the results)
• ShellExperienceHost.exe: what it is and how to fix high CPU, memory or crashes
• Windows Explorer crashes on right-click: how to find the cause and fix it
• Taskbar icons missing in Windows 11 or 10: how to get them back
• How to open Command Prompt as administrator in Windows 11 and 10

Official sources:

• Microsoft Support: Use the System File Checker tool
• Microsoft Learn: Start menu troubleshooting guidance
• Microsoft Learn: Modern, inbox and Microsoft Store apps troubleshooting guidance