Internally, Duplicati will ask the library to stop doing whatever it is doing. However, it is not possible to always stop the process, so in some cases it may take a little while before it responds. In some cases, and maybe the SMB library is especially bad here, the stop signal is simply ignored and the processing can hang indefinitely.
With the latest canary release, we have added the option to run in an isolated process. The spawned process then runs the backup. If you click “abort”, this will then kill the process completely so it does not matter if it handles the stop signal. It is still an experimental feature as we might need to tweak some option transfers between the processes.
You can try it out with the 2.3.0.103 release, and we are always happy to hear feedback:
Release: 2.3.0.103 (Canary) 2026-05-22