Can you give us a clue as to what the error message says?
What version of Lightroom? Go to Adobe Photoshop Lightroom and tell us the exact version number.
What operating system?
LR encountered error when reading from its preview cache & NEEDS TO QUIT. LR will attempt to fix this problem next time it launches
This happened a couple of weeks ago. I have seen this message ever since but I can launch and use LR with my other external hard drive.
LR 5 on an Acer Aspire V3 WITH WINDOWS 10.
Thanks for the reply.
Exit LR if it is running.
Using File Explorer, go to the folder containing your catalog (*.LrCat).
Find the previews folder for that catalog (Similar name, ends in "previews.LrData".)
Delete the previews LrData folder; delete nothing else.
Start LR, it will recreate the preview cache as needed.
Thanks, It worked, very happy.