This is the forum for discussing development of LR plugins. You'll have more success posting in the main LR user-to-user forum: Photoshop Lightroom.
But before you post, a search using the "Search Communites" box in the upper right shows there are many threads discussing their error message: https://forums.adobe.com/search.jspa?q=Lightroom+encountered+an+error+when+reading+from+it s+preview+cache+and+needs+to+q…
thank you for link.
Followed the directions for replacing the Previews Folder.lrdata. Actually, renamed it OLD and restarted LR up. Started right up, but now ALL my photos have NO previews and an exclamation mark and say "Lightroom has encountered problems reading this photo. You will not be able to make adjustments to this photo"!!!
Figured out what happened to my previews! Got hit with CryptoWall virus/trojan and all my files were corrupted (encrypted). I mean everything on my hard drive, attached backup drives, everything. Now in process on restoring everything from online backups, then will have to get LR back up and running, etc.
Also getting rid of the old PC in the process and going to Mac. Still need to protect against viruses, but chances are substantially diminished. Have LR duplicate with files on my Mac laptop, so will probably start with those as base.
Thank you for your help.