Data Transfers · Progress, pausing and history
What happens to my files when I cancel a transfer?
Short answer: Cancelling stops the transfer without undoing it: finished files stay at the destination and untouched files stay at the source. A cancelled Move never leaves a file in neither place, and large downloads keep their fetched pieces.
Cancelling stops the transfer where it is. It doesn't undo anything: files that had already finished stay at the destination, and nothing that hadn't been sent is touched at the source. For a Move, originals are only removed after their copy is checked, so a cancelled Move leaves every file in one place or the other.
For a large single-file download, the pieces already fetched are kept after cancelling, so starting the same download again doesn't throw that work away.
A cancelled transfer stays in the list (marked Canceled) until you Remove it or use Clear completed.
Related: Pause and resume · Is Move safe?