Following the purchase of a DSLR camera, I have switched to using raw mode and Adobe Lightroom for post-processing of these photos. Up to now, I have been using Google Picasa to organize and tag my photos. Initially, my collection of photos worked just fine in Lightroom as I invested hours of work of retouching my favourite photos for my gallery. After doing some mass tagging and organization of photos in Picasa, Lightroom stopped reading many of my JPEG photos taken across many years with several different cameras.
Now, when selecting a photo in Lightroom’s Develop mode, I would see a error message:
"The file appears to be unsupported or damaged."
Stupid Lightroom doesn’t provide any additional details or repair options, though further edits to the photo in Lightroom were disabled.
After some research, I found that the metadata headers were still intact, but had been saved by Picasa using a format that isn’t supported by Lightroom.
Cause of Problem
For some reason, Picasa is changing the metadata of the image. I was able to reproduce the problem simply by adding a tag in Picasa, removing it, and then trying to import the JPEG into Lightroom.
The easiest solution is to re-add the tags you removed using Picasa, and then remove them again using Lightroom. If you don’t remember which tags you removed, adding some new tags may work just as well. I found that the length (in characters) of the added tags had to be greater than those I removed.