Last time I updated Lightroom classic it was a disaster. Spent hours with LR support. Catalog lost collections. How can I avoid this if I update to 15.4.1?

V 15.4 and 15.4.1 (if you didn’t upgrade to 15.4) will tell you that it’s going to upgrade your catalog and save the old pre 15.4 catalog as a .zip file in a folder called “Old Lightroom Catalogs”. At this point, if you have multiple LrC catalogs, be sure that LrC 15.4.(X) is upgrading the correct one. If you have multiple catalogs, the upgrade process will have to run for each one in turn. 

The upgrade worked fine for me on both Win11 and MacBook systems. However, I and several others experienced a very long delay the second time I started LrC 15.4 with the new catalog. When you click to open LrC, it seems nothing is happening. If that happens, just keep hands off. It might take hours to load the catalog if you catalog is really large. Subsequent LrC startups go fine, with previews loading even quicker for me.

I used V 15.4.1 today to process a major music event. All worked just fine. Collections came through all OK.