When I close Lightroom 6 (version 6.9) and it trys to back up, I get the message "Lightroom encountered an error when reading from its preview cache and needs to quit". It then says that Lightroom will attempt to fix next time it launches. i have relaunched several times and it has not fixed. Any ideas what I should do?
Exit LR if it is running.
Using Mac Finder or Windows File Explorer, go to the folder containing your catalog.
In that folder, delete the folder with the same name as your catalog but ending with "Previews.LrData".
Do NOT delete the LrCat file.
Restart LR, and it will create the previews from scratch.
With Lightroom closed, delete the preview cache. In your operating system, go to the folder which contains you Lightroom catalog and delete the subfolder there whose name ends with Previews.LRDATA. Do not delete anything else.
Brilliant- it worked.