2 Replies Latest reply on Feb 2, 2015 10:38 AM by jenbrake

    Lightroom and preview cache and other related issues.


      So I went to open up LR on Friday afternoon (1/30/15) and it wouldn't open. I can't think of anything I had done differently to it, nothing new with my computer. But when I clicked to open it, I got a screen that read, "The Lightroom catalog named 'Lightroom 5 Catalog' cannot be opened because another application already has it opened." I sought some outside advice. I made sure there was nothing even open in the task manager (after having already shut down and re-booted my computer a couple of times) and then opened my most recent backup catalog. I also deleted the "lock" file.


      I was then able to import new photos to LR, but noticed that one folder was missing--the one from 1/29/15. That is likely the last folder I was working in before this whole mess started. After doing some clicking, I could see that those pictures were still in a catalog and on my hard drive, but I could not open a catalog with them in it. If I tried, I got a screen that read, "Lightroom encountered an error when reading from its preview cache and needs to quit."  On the advice of a computer guy and with the reassurance that I can always restore if necessary, who told me to delete the preview cache file. I thought that's what I did, but now I'm not sure. I deleted a huge file folder entitled "Lightroom 5 Catalog previews.lrdata.  This did allow me to open LR, but I had a few days' worth of missing folders and decided to restore what I had just done and seek advice again. Now I'm being asked this if I want to merge the deleted folder with a previews folder from 8/23/13.


      Do I want to merge these? The August 2013 date is about the time I purchased LR. I have done nothing since seeing this.  So I first ask if I should merge these and restore the files OR just keep the deleted previews folder in the recycle bin, then have LR find the missing folders.  And secondly, what the heck happened to make this happen in the first place?  Any help is greatly appreciated.  Thank you!

        • 1. Re: Lightroom and preview cache and other related issues.
          JimHess Adobe Community Professional & MVP

          You didn't need to open your latest backup catalog. All you needed to do was to delete the lock file that you found. Then your current catalog which has all the images in that would have opened. The lock file is used by the database engine that drives the Lightroom catalog. It is supposed to be deleted whenever Lightroom closes. But sometimes Lightroom doesn't close normally and that file gets left behind so it has to be deleted manually.

          • 2. Re: Lightroom and preview cache and other related issues.
            jenbrake Level 1

            Thank you for your reply.  Very simple and helpful!


            However, I am now a bit lost as my catalog is messed up.  I am missing folders in the catalog that I have open.  When I helped LR find them on my hard drive, I got a popup question that read, "The selected folder or one of its subfolders is already in Lightroom.  Do you want to combine these folders.  I clicked "Merge" and then the folder completely disappeared from the list of folders.  I still see it in the correct place on my hard drive, but I can't get to it from LR now.  I assume those missing folders (and another folder full of pics I imported but now don't see listed in the catalog) are in another catalog as I think I have been working with the backup catalog that I opened at the beginning of this whole mess.  Can you help me get everything current and in one catalog again?  Thank you.