Catalog

No, Lightroom did not tell you the catalog was 'full'. That is simply not possible. Lightroom asks you to make a backup copy of the catalog on quit. That has nothing to do with the current catalog being 'full', it is just a precaution for if you get a problem with your existing catalog. Like any other backup system (such as Apple Time Machine) is. Making a catalog backup should not let you lose any images, and so deleting old catalog backups from time to time doesn't either. That is probably what you read in these forums. The only way you could lose images this way is if you deleted the wrong (most recent) catalog and continued with an older backup copy.

The question is what you mean exactly with losing images. Are they gone from Lightroom completely? Are they still shown in Lightroom, but does Lightroom say they are 'missing'? You say you now have 40,726 images in the catalog. How many should that be? And what kind of images do you think you have lost? Older ones? The latest ones?

Lightroom never says that the catalog is almost full, because there is no limit to the number of photos. There are photographers who have a single catalog with a few million images! My own catalog has 'only' about 200,000 images.

If you deleted earlier catalogs that contained information not in your current catalog, and you do not have backups, then I'm afraid there is nothing anybody here can do to help you retrieve that. If you do have backup copies, then we can help you merge these old catalogs with your current catalog.

I am having a similar problem - I cannot locate hundreds of photos after Lightroom said the catalog was nearly full.  This forum said that all of the catalog's are saved, and I should delete some of the earlier catalog's.  Doing this caused me to lose a few years of virtual photo's and edits.  I have been trying to reinstall catalog's for days - some came back but most not.  I am getting the runaround at Adobe since they no longer have support for this version.    Where can I find professional help?