Previews Disappeared

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Today’s Question: The other day I launched Lightroom only to see a message that there was a problem with my catalog and it needed to be checked. When the check was complete, Lightroom indicated that the catalog was damaged and needed to be repaired. Thankfully that was successful, but in the process all of the previews for my images changed to gray rectangles. As I browse folders the previews are being rebuilt, but is there a way to build previews for all images at one time?

Tim’s Quick Answer: You can indeed build previews for all images in your Lightroom catalog. Simply navigate to the All Photographs collection in the Catalog section of the left panel in the Library module, select all images, and then go to the menu and choose Library > Previews > Build Standard-Sized Previews.

More Detail: While I’ve certainly known photographers who have ended up with a Lightroom catalog that was corrupted to the point of not being able to be recovered, in many cases Lightroom will be able to repair whatever problems occurred with the catalog so you can get back to work without losing any information. Of course, this underscores the importance of backing up your Lightroom catalog on a somewhat regular basis.

When a catalog is repaired, I have found that the previews file becomes problematic. Fortunately, it is very easy to generate new previews for all images in your Lightroom catalog.

As noted above, the “All Photographs” collection found in the Catalog section of the left panel in the Library module enables you to view all images in your entire Lightroom catalog. You can then select all of the images by choosing Edit > Select All from the menu.

It is important to note that in order to note that in order for Lightroom to build previews for your photos, the source image files must be available. For example, if your photos are stored on external hard drives, those drives must be connected to the computer in order to build previews.

To build previews for the selected photos, you can then choose the appropriate option from the Library menu. When you navigate to the Library > Previews submenu, you’ll see that you can build Standard previews or full resolution 1:1 previews. Select the option that makes the most sense to you, and Lightroom will get to work.

The process of building previews for an entire catalog can take considerable time. Obviously, the specific time will depend upon how many images are in your catalog. However, you can expect the process to require several hours, and possibly a full day or more. Fortunately, photos that already have previews will be skipped, meaning that Lightroom won’t waste time building previews unnecessarily. That also means you can cancel the task and restart it at a later date if needed.