Lightroom could not import this catalog because of an unknown error

Lightroom -- Import from Catalog
Lightroom -- Import from Catalog

When I travel for a shoot, or work on organizing a new project in Lightroom, I often create a new separate catalog just for a particular set of images. The smaller catalog runs faster and keeps things simple. When everything is processed, I'll then import the smaller catalog into my master catalog by going to: File -- Import from Catalog:

Recently I encountered an issue with this workflow -- when trying to import one of these small working catalogs into my main Lightroom 3 catalog I got an error message that said: Lightroom could not import this catalog because of an unknown error:

Lightroom could not import this catalog because of an unknown error
Lightroom could not import this catalog because of an unknown error

Not a very helpful error message, huh?

After some troubleshooting, I figured out the conditions that cause this error to occur, and how to fix it. The problem occurs if the catalog you're trying to import was upgraded from Lightroom 2 to Lightroom 3, and there are photos in the catalog that are offline or missing, as indicated by the question-mark icon in Library Grid View:

Lightroom Library Grid View question mark
Lightroom Library Grid View question mark

The question mark indicates that you've moved or deleted photos outside of Lightroom, and Lightroom no longer knows where to find the file. To remedy this situation, click the question mark and locate the file, or turn on the external hard drive where the images are stored. If the files have been deleted, you can click delete and remove the images from the Lightroom database.

When you have resolved all of the images that are offline or missing in your smaller catalog, you will be able to import the catalog into your master catalog. If you haven't created extensive collections in this catalog, another solution would be to create a new catalog for these images in Lightroom 3. Catalogs that are native to Lightroom 3 don't seem to have this problem (i.e., catalogs native to LR3 with offline or missing images will import into another LR3 catalog just fine). If you choose this fix, make sure to write your metadata changes to XMP so you don't lose your work.

I hope this bug fix saves you time!

Note: I'm running Mac OS 10.58 10.64 with Lightroom 3.0.

Update: I ran this issue by Victoria Bampton, The Lightroom Queen, who let me know that duplicate files can also cause this error message (i.e., the same photo is in both catalogs). Hopefully this issue will be fixed in LR3.2.

Update: Tom Hogarty, the Product Manager for Lightroom at Adobe, let me know they're working on a fix for this issue.

Update: According to a reader's report, this issue looks to be fixed in Lightroom 3.2 (release candidate).

Update 8/29/2010: I found another variation of this bug. I was trying to import a working catalog that I recently created in LR 3.0 into my master catalog. The Library -- Find Missing Photos command did not yield any images, but I kept getting the Lightroom could not import this catalog because of an unknown error message. Turns out there were 3 images that WERE missing, but Lightroom wasn't finding them. Here's how I figured it out:

  1. In the working catalog, go to Library -- Show Photos in Subfolders, and make sure this feature is unchecked. This will give you an image count for each individual photo in your catalog.
  2. In the Grid View, make sure you have Index Numbers turned on to count the actual thumbnails. You can turn on Index Numbers by right clicking a thumbnail in Grid View, choosing View Options, and then checking Index Numbers.
  3. Now go through folder by folder and match the folder image count on the left, to the index number count in the Grid View. In my case there were 3 TIF files that Lightroom was not seeing.
  4. Next I saved the metadata to the files in the folder with the missing images by going to Metadata -- Save Metadata to Files.
  5. Highlight the folder on the left, right click, and select Remove to temporarily remove the folder from your catalog.
  6. Now go back to the file menu and choose Import Photos to re-import the folder. In my case the image counts now matched up, and I was able to import the working catalog into my master catalog.