In the United States, it’s canceled. In Great Britain — and I assume in Canada — it’s cancelled. Similarly, in the U.S., we are worried about the cancelation of the entire season. In Canada, they are worried about cancellation.
This should not be one of those “both are correct” situations. The Associated Press manual says it’s one L here, and two up there. It’s also not correct to colour with crayons, or join a labour union — unless you’re a subject of the realm.