Delete the preview cache. It is a subfolder whose name ends with Previews.LRDATA in the folder which contains your catalog (.LRCAT) file. Delete only this Previews.LRDATA subfolder, do not delete the .LRCAT file or anything else.
I have the same problem. Deleted the previews.lrdata file and relaunched Lightroom. Same error message and the previews.lrdata reappears. HELP.
Then you deleted the wrong previews.lrdata folder.
Use your operating system to search for all previews.lrdata, and delete every one of them.
I've done that but still no luck. By the way I'm using Lightroom CC, if that makes any difference. Being new to LR I only put a few images in the catalog for me to practice. I then deleted the images from outside of LR. This is when the error message started to appear. I have uninstalled and reinstalled LR, but it still comes up with the same message. Should I create a new catalog rather than LR create a default? It's very frustrating!!!!!!!!!!
- The error message that you are having clearly states that the issue is with the Preview file, but as you said you have already tried to delete but it doesn't resolve your issue.
- If you want to continue with your old catalog then you need to delete the Previews.lrdata file associated with that catalog and it would reside at same place where your catalog is stored.
- Else you can try creating a new catalog by holding Alt key on Windows and Option key on Mac while Launching Lightroom.
Used the Alt key, created a new catalog, everythings fine.