Many years ago, I wanted to use Firefox sync to migrate profile and bookmarks from one OS to another. I don't know if it's still the case, but at the time ther

Many years ago, I wanted to use Firefox sync to migrate profile and bookmarks from one OS to another. I don't know if it's still the case, but at the time there was an automatic periodic and a manually triggered sync, with a button and sync icon (like ). I triggered the manual sync by clicking on the button. The icon spinned for a few seconds and then stopped. I interpreted this as the sync being finished, formatted the drive, installed the new OS, installed Firefox, set up sync, and waited for the profile/bookmarks to arrive. Nothing happened. Apparently (as per their issue report response) at the time, the spinning of the sync icon was only showing that the data had been written somewhere on disc and registered for the next periodic sync. The button did NOT trigger the sync itself. This was very frustrating and a good reminder to never rely on a single sync/backup. Also an interesting example of bad UX. Dropbox was already around at the time IIRC, and its stopping rotating sync icon indicated the actual sync to be finished, as one would expect. Again, this was many years ago, and I think I remember reading that they reimplemented sync from scratch some time later. I'm still using Firefox, but not their sync. Maybe time to give it another chance.