Backups & restore points · Speed, progress and the first backup
What happens if a backup is interrupted?
Short answer: Nothing is lost. An interrupted backup — quit, sleep or a dropped network — continues from where it stopped next time and never re-uploads what's already saved.
Nothing is lost. If a backup stops partway — you quit the app, the Mac sleeps, the network drops — it continues from where it left off next time and never re-uploads anything it has already saved.
If Storage Studio closed while a backup was running, the card says so — for example "The last backup didn't finish — Storage Studio closed while it was running. It picks up where it left off, so nothing is lost." Press Back up now to carry on immediately, or let it resume on its own.