Today’s Question: I just tried to load my Lightroom catalog and got a message it is corrupt. I tried all the suggestions Lightroom made to no avail. Any suggestions? I have a week-old backup, but will lose a fair amount of data if I have to utilize it.
Tim’s Quick Answer: I would first make some additional efforts to open the catalog, but failing that would want to either restore from a backup or re-import into a new catalog if you had enabled the option to automatically write metadata updates to XMP.
More Detail: Naturally the ideal solution here would be to regain access to the Lightroom catalog that has become corrupted. Unfortunately, if the catalog has become corrupted there isn’t much chance that you’ll be able to recover it. However, you might try quitting Lightroom and then confirming that none of the temporary files are included along with your Lightroom catalog. One simple way to test this out is to copy the corrupted “lrcat” file (the actual catalog file) to a different location, and then double-click to open that catalog file in Lightroom. If that fails, chances are you won’t be able to recover your catalog.
If you had previously enabled the “Automatically write changes into XMP” on the Metadata tab of the Catalog Settings dialog in Lightroom, you can recover most of the information from your corrupted catalog by simply creating a new catalog and importing all of your photos into that catalog, using the “Add” option at the top-center of the Import dialog.
It is very important to keep in mind that some information from your original catalog will be lost if you take the approach of creating a new catalog and importing all of your photos into that catalog. For example, pick and reject flags, membership in collections, the history in the Develop module, virtual copies, and some other details that relate to Lightroom-specific features are not written to your images when you enable the “XMP” option noted above. However, all standard metadata such as star ratings and keywords will be retained if you had previously enabled the “XMP” option in the Catalog Settings dialog.
The last option, as noted in the question, is to recover from the most recent catalog backup. Obviously this means you will lose any information that was added to the corrupted catalog since the time of your last backup. You may therefore need to update information for some of your photos, and even re-import photos that had been imported after your latest backup. But at least this approach will provide you with most of the information that would have otherwise been lost in the absence of a backup.
This type of situation does underscore some of the challenges associated with the use of a catalog in Lightroom. There are many advantages to having that catalog as well, but it is very important to protect yourself from the risk of corruption of your Lightroom catalog, through frequent backups and other workflow practices.