Library module missing thumbnails

[bly]

Operating System:mac high sierra
Exact Lightroom Version (Help menu > System Info):6.14

Hi,
Having problems with LR after cancelling back up of computer. I have been running 6.14 with high sierra successfully, but now when I open LR the image boxes appear, but no images. I have reloaded LR 6 and 6.14 and have tried opening from back-up .ircat file, but still no images. Hope someone can help.

 

[Johan Elzenga]

Looks like your previews cache is corrupted. Open the Lightroom catalog folder and remove the 'catalogname previews.lrdata'. Place it somewhere else, outside the folder (or trash it). Now start Lightroom. Lightroom will rebuild the previews cache, so at first you won't see any thumbnails but then they should start to appear one by one.

 

[bly]

Thanks John, this does work, but LR only builds previews for images displayed on screen, so am having to rebuild 146,449 previews 40 at a time. Previews are still there when I quit then reopen LR and all latest editing is there too.

The problem I still have though is that all my backups are like this. Could the problem be because LR is compressing my 4.73GB catalogue into a zip file? I opened the zip file by double clicking which revealed a 4.73Gb .ircat file and 152KB .irdata file. Now I have begun rebuilding the previews the .ircat file is rapidly increasing in size.

I have tried searching on-line for how to restore from a zip file, but I don't understand what is being said. Hoping someone can help with understanding restoring from zip files and if this is the problem.

 

[Johan Elzenga]

Of course all your backups have the same problem. The thumbnails are not in the catalog file, they are in 'previews.lrdata' and Lightroom does not backup this file, only the catalog (.lrcat) file. So using a backup catalog file doesn't change anything in this respect, and the fact that catalog backups are zipped has nothing to do with it either. There is no way to quickly get your previews back, unless you've made a backup of them too. Do you use Apple Time Machine to make general backups? If so, you could try to restore the 'previews.lrdata' from a Time Machine backup from before the problem occurred.

It is indeed a nuiscance that Lightroom only builds previews for those images that are visible in the grid. You have two options if you can't restore the previews from a backup:
1: Accept it. Over time, Lightroom will have rebuilt more and more thumbnails, so over time this problem becomes less and less.
2: Go to 'All Photographs', select all your photos and then choose menu 'Library - Previews - Build Standard-sized Previews'. That forces Lightroom to build all previews, also the ones that are not visible in the grid right now. It will take a long time to rebuild 146,449 previews however. The rate is about 1 second per preview in my experience, so do the math...