In their answer here, Sarov says:
When achieving the Sprint Goal is unlikely then the Sprint should be cancelled
Let me offer a revised formula
When the Sprint Goal is in danger then invoke your emergency procedure.
- Change the way the team does the work.
- Do something different.
- Get help, usually by offloading backlog to someone else.
- Reduce scope.
- Abort the Sprint and replan.
- Inform management how the emergency affects release dates.
So while cancelling the Sprint is an option, it should be considered only as a last resort.
Cancelling a Sprint when the Sprint Goal is looking unlikely to be met is an extreme position to take. It may ensure you never have a failed Sprint but I don't consider it a formula for success!
It's a bit like saying
When the airliner is in danger of not reaching its destination then immediately conduct a forced landing
From my naive understanding of aviation, it would seem better to
- request air traffic control to find an alternative destination
- invoke the emergency procedure
The Scrum Guide offers a different formula:
A Sprint would be cancelled if the Sprint Goal becomes obsolete...
In general, a Sprint should be cancelled if it no longer makes sense given the circumstances. - Official Scrum Guide
The examples in the Scrum Guide makes it clear the circumstances the authors have in mind are those external to the team. They also make it clear that Sprint cancellation is far from routine:
due to the short duration of Sprints, cancellation rarely makes sense. - Official Scrum Guide
As a Product Owner, I would joke to my Scrum Team that I had a personal goal to one day have the chance to cancel a Sprint, a light-herated way of communicating the idea that a cancelled Sprint is rarely seen in the wild.
Indeed, once (and only once) have the circumstances actually arisen for me. My Scrum Team was halfway through a Sprint whose Sprint Goal related to a compliance project. I was in a meeting with Stakeholders when someone mentioned, almost as an aside, that they cancelled the project that morning because legal counsel had concluded the project's outcomes were unnecessary. But even in these circumstances, we decided as a team to not cancel the Sprint. As is often the case, there were Sprint Backlog items that did not directly relate to the Sprint Goal but everyone still wanted to be completed. Taking out the compliance project items ply left a three days' 'capacity' in the Sprint, and some spikes were played instead, to everyone's satisfaction. A major consideration was not upsetting the Sprint cadence (Mon-Fri etc)