There are a few clues that your preview cache may be corrupted. The most obvious is Lightroom showing an error message telling you that it’s corrupted (“Lightroom encountered an error when reading its preview cache and needs to quit.”), or that it tried to repair it unsuccessfully.
Alternatively you might find that Lightroom displays the wrong preview for some of your photos, some previews or thumbnails disappear when the photo is deselected, or the photo only shows in the Develop module.
In Lightroom CC/6, Lightroom tries to fix the preview cache automatically when it restarts. If this doesn’t work, or you’re using an earlier Lightroom version, you can fix it by manually rebuilding the preview cache:
- Find your catalog on the hard drive. If you can open Lightroom, go to Edit menu (Windows) / Lightroom menu (Mac) > Catalog Settings > General tab and press the Show button to open an Explorer (Windows) / Finder (Mac) window, then quit Lightroom. If you can’t open Lightroom, and you don’t know where to find your catalog, you’ll need to search for *.LRCAT les.
- Using Explorer (Windows) / Finder (Mac), move or rename the previews folder (*Previews.lrdata) and restart Lightroom.
- Lightroom can now rebuild the previews from the original files. Select all the photos and go to Library menu > Previews > Build Standard-Sized Previews and leave it to work, perhaps overnight as it takes a long time. If any of the photos are offline (e.g. stored on disconnected external hard drives), these previews will remain blank until you reconnect the drive.
- Once you’re happy they’ve all rebuilt, you can delete the previous previews folder (*Previews.lrdata) if you haven’t already done so. I don’t usually recommend deleting the old previews before building new ones, just in case there are any missing original files, and the previews are the only copy you have left. If you’re comfortable that you still have all of your original files available, then you can delete the old previews before building the new ones.
Hi I got a new computer and then I opened my previous catalog and I only have gray squares. my original files are on many different hard drives. I just want my previews back so I can reference the many shoots I have occasionally. I dont want to rebuild previews. Why can’t it connect to my large orginal lrdata folder?
Did you copy your Previews to the new computer at the same time as the catalog?
Moving to a new computer usually means the drive names / letters have changed and the foles need relinking.
https://www.lightroomqueen.com/lightroom-photos-missing-fix/
I had a problem like this now for almost a week, with LR Classic and tried deleting the preview file(mac) with no luck what eventually realised that when i updated LR the new catalog file must have been corrupted, so i went back to the old one before the update made a copy then imported it again, so LR could convert it to the new V10 catalog now everything is fine.
Sounds like the upgrade didn’t work properly for your catalog and previews. Glad re-running has sorted it!
I went to LR catalog and deleted the PREVIEWS file. But I am STILL getting the “ERROR” box message. Any further tips?
You’re getting the error immediately after deleting the previews? Or are a little time has passed?
There are two things that come to mind. Perhaps you deleted the wrong previews, or perhaps there’s a problem with the drive. Those are the most likely suspects, but if that’s not it, post on the forum (linked at the top of the page and we’ll help you troubleshoot further. (Two way conversation is easier on the forum interface.)
I have a disk cataloger that is used for searching for all sorts of things. I found that it was including Previews.lrdat and disabled that folder from being scanned. No more problems.
That’s a good tip, thanks for sharing Duane.
A question as I am about to perform this fix . My photo files used in Lightroom are located on three external hard drives which cannot all be connected at one time. Can the I build the previews multiple times to recover the files on each drive? Thanks
Yes, that’s fine Ralph.
I followed the process exactly and its churning through my photos. But, library view, I can’t see any new previews appear. Can this be good? Initially, I did not get an error message from LR, just every photo grayed out except in develop . . . .
I would expect some to be turning up David, but it may be outside of your current view. Tried scrolling?
My LR catalog got hung up a couple of days ago and now the previews aren’t showing up, except the last three I’m working with. I am unable to delete or rename my previews folder. I get this error “The Finder can’t complete the operation because some data in “2016-LR-JUNE-FORWARD Previews.lrdata” can’t be read or written. (Error code -36).” Any suggestions?
Error code -36 sounds like an OS X error – likely a problem with your hard drive or disk permissions. Phoning Apple would be your quickest solution.
I deleted Previews.lrdata but the error still comes up!!! I need to work!!
You definitely deleted the Previews.lrdata for your active catalog, and not another random catalog? If so, post it at http://www.lightroomforums.net and we’ll consider other possible troubleshooting. I’d maybe try moving the catalog onto another drive in case it’s being caused by a hard drive failure.
How to prevent this problem because it happens very frequently despite renaming the preview folder.
If it’s happening more than once in a blue moon, I’d be asking why. Either Lightroom’s not being shut down properly, or there’s a hardware problem. I’ve also heard of some issues when the catalog’s stored in certain cloud storage folders (e.g. Box.net, OneDrive)
Thank you for helping
If you are using a sync like Google Drive then just don’t. 🙂
https://gramachree.wordpress.com/2016/02/09/synchronisation-and-lightroom-encountered-an-error-when-reading-from-its-preview-cache-and-needs-to-quit/
Yes, I’ve heard of a few issues with syncing via Google Drive. Dropbox has been working pretty well for some years, if you’re looking for an alternative.
Thanks for posting this tip on the interwebby. . . I was just starting to go into panic mode 🙂
Followed the directions. It works. It takes 2/3 second to build each preview. I’m in for a long night.
If you’ve used Library menu > Previews > Render Standard-Sized Previews, you can leave it running and go to bed!