To cancel a booking in a period that were blocked?

[Fredric1]

I just published our house - on airbnb  and got a booking in a period I had blocked, but the we still got a reserveration. Not sure how this happened ? and how to cancel the booking without any damage to either me as host or the nice guest

[Helen3]

Don't cancel the book (see host cancellations Airbnb Help Centre.

There is a technical fault which means this sometimes happened. If you blocked the dates Airbnb can see this and will cancel the booking for you and then you won't be penalised.