Shared Lightroom catalog

I share my catalog (about 70,000 images) between my laptop and desktop.  The catalogs are synced to each computer using Dropbox.  Most of the time it works perfectly without any problems.  Howver, every once and a while I will get a corrupted catalog.  This happens when I open the catalog on a computer before it has finished syncing the most recent version from Dropbox.  I will then have to get a backup from Dropbox.

My guess is that when you are getting corrupted files, it is because two people are trying to edit on the catalog at the same time and Google Drive's sync is getting messed up and corrupts the file.

It may help to use small dedicated Catalogs in the studio. You can (for example) set up your current Catalog the way you like to work, with whatever standard keywords you use, then highlight just one image and Export as Catalog (choosing to include only highlighted images). This creates a new (nearly) empty, separate Catalog file. You can then employ this as a template, making a new separate copy of that into the laptop before each session shooting in the studio. Import fresh images into this copy Catalog. Employ a consistent folder filing scheme too for the images, the same scheme as you do for images in the main Catalog. Then these new images will have a natural home within the main storage, that they can slot right into as a set. Also the contents and edits present in this "shoot" Catalog can be merged into your main Catalog using "Import from another Catalog". Any needed re-pathing of the transferred images should then be straightforward.

If there are two people wanting to develop pictures coming off two laptops, at the same time, their two "shoot" Catalogs can remain separate for the moment, so they don't get in each other's way. And then only merge those into the main Catalog later. Or two shoot Catalogs can be merged into one, and then later into the main Catalog - or (not advised) retained separate permanently - all kinds of workflow alternatives.

The main issue here is that LrC is a single-access database system whose integrity relies on LR's normal methods of operation being used. While in active use, this database may not be in a state that is suitable for copying. To maintain two different local copies of that database (let alone four!) and synchronise these back and forth at the file level as if they were conventional files, is always going to invite problems IMO. Or if the sync sometimes does not happen because the database is in use, then there's a risk of someone working on a non-latest copy and then having a nasty reconciliation problem.

One way to work between two desktop computers and ensure that everything is handled cleanly, may be to keep the main Catalog on an external drive that can be passed back and forth between them as needed. This guarantees there is one definitive copy only, backups aside - it is an inherently 'stable' rather than 'unstable' method. That decision about where the Catalog lives, is independent of where the image files are to live. Those may e.g. live on an external drive or in a  network storage location that appears the same way to both computers, then it makes little difference which computer you are using (aside from central presets, profiles, watermarks etc which may differ). But again, to maintain duplicate copies of all these image source files on both computers may be an unneeded complication, and certainly creates a synchronisation issue that would not otherwise exist.