Can't Edit Jpgs

[RBSPhotog]

I recently had many slides coverted to jpgs. I moved them onto my desktop hard drive. I then imported the jpegs into Lightroom CC. I spent a few hours adding in the keywords as I imported.  This all went smooothly. However when I tried to edit in LR or in PS, I get a "File Not Found" error. I then opened PS and opened any of the jpgs from their location on my desktop hard drive.  Why can't I edit in LR or PS these files in or from LR CC?

[Jao vdL]

Which version of Lightroom are you using. The mentin of Lightroom CC sounds like this might be the cloud-based version instead of Classic. It could also be a very old version of Classic. How this works depends completely on what version you are using. Do a system info in the help menu and post the results here. 

[JohanElzenga]

After you imported the images, did you move them to a different location on your hard drive or changed the name of any of the folders? Lightroom makes a reference to the image in its catalog. It stores the 'path' to the images. If you change that path outside Lightroom, then Lightroom doesn't know anymore where the original image is. It can still add metadata to the catalog, so you can still add keywords to the images, but if it needs to get the original for something, then it will give you that "File not found" error. 

https://www.lightroomqueen.com/lightroom-photos-missing-fix/