I cannot open images and get "Class not Registered" error

Hi Ivor,

Thank you for being a part of Windows 10.

I would like to know, how you are trying to open the pictures. Is it though the Photo app?

I suggest you to run a System File Checker (SFC) scan to check for any file corruption. SFC scan will scan for corrupt system files on the computer and repair them.

1. Press Windows key + X, click Command Prompt (Admin).
2. In the Command Prompt, type the following command, and then press Enter:

         sfc /scannow

Hope the above information helps. Reply with necessary information and the result to help you further.             

Thank you.

This may work for some people, but did not fix my issue. After running the scan, there were no problems found. I've tried to change the current photo viewer app -TWINUI - to Windows Live Photo Gallery and Photo Viwer, but Windows 10 won't do it. Are there any other fixes?

Additional information added after first comment above. Searching for fixes to this issue, I came across this site -- tenforums.com -- where I found a couple of answers. One involved a download, the other was manually changing settings through the control panel (not the Windows 10 Settings > System > Default Aps , which would not let me choose anything else but TWINUI). I chose the manual changes path, and it seems to be working. Good luck!