If you try to open a program, or a picture/photo in Windows 10, and you receive the error "Explorer.exe: Class not Registered" continue below to fix the problem. The "Class not registered" error, usually indicates an unregistered DLL file that is necessary for the program to run correctly.
A DLL (Dynamic-link library) file, is a file that contains code and data that can be used by more than one program at the same time and helps reduce code and memory usage.
How to FIX: Explorer.exe Class not Registered error in Windows 10.
Important: Before applying the methods below, try the following:
Press CTRL+SHIFT+ESC to open the Task Manager. Go to the Startup tab and select and Disable any apps that don't need to be loaded when Windows starts. (e.g. iCloud, Spotify, etc.). When done, restart your computer and check if the problem persists.
Method 1. Uninstall Latest Updates.
If the "Class not Registered" error occurs after you install updates in Windows 10, go ahead and uninstall the installed updates.
1. Go to Start > Settings > Update & Security > Windows Update.
2. Click View update history.
3. Select the Security Update for Microsoft Windows (KB5000802) and click Uninstall.
4. After uninstall reboot your PC and see if the problem persists.
Method 2. Reset Default Apps.
1. Go to Start 
> Settings > Apps.
2. Choose Default Apps on the left and then click Reset
3. Then click Choose default apps by file type.
4. At this screen, ensure that the .JPEG & .JPG files are open with the Photos app.
Method 3. FIX Windows corruption errors with DISM & SFC tools.
1. Open command prompt as administrator. To do that:
1. In the Search box type: cmd or command prompt
2. Right click on the command prompt (result) and select Run as Administrator.
2. At the command prompt window, type the following command & press Enter:
- Dism.exe /Online /Cleanup-Image /Restorehealth
3. Be patient until DISM repairs component store. When the operation is completed, (you should be informed that the component store corruption was repaired), give this command and press Enter:
- SFC /SCANNOW
4. When SFC scan is completed, restart your computer.
5. After restart check if the "Class not Registered" error is resolved.
Method 4. Uninstall and Reinstall Photos App.
If the Windows 10 Photos App is not working, then proceed to completely remove the Photos App from Windows 10 and then reinstall it. To do that:
1. At the search box, type powershell
* Note: On Windows 8/8.1: Press the Windows 
+ S keys to open the search box and type powershell.
2. Right click on Windows PowerShell on the results and select Run as administrator.
3. In PowerShell, give the following command to remove the Photos App:
- Get-AppxPackage *Microsoft.Windows.Photos* | Remove-AppxPackage
4. Close PowerShell.
5. Finally open the Microsoft Store to download and install the Photos App again. To do that:
1. At Microsoft Store's search box type: Photos and click on "Microsoft Photos" App.
2. Click the Get button to reinstall the Photos App on your system
That's it! Which method worked for you?
Let me know if this guide has helped you by leaving your comment about your experience. Please like and share this guide to help others.