From the RAF News Website:

Following the earlier announcement to postpone the 2020 RAF Cosford Air Show until September, we have now taken the difficult decision to cancel it for this year.

The decision to cancel has not been taken lightly. The Royal Air Force relies on support from international air forces and assistance from local civilian services, our commercial sponsors and volunteers to stage the Cosford Air Show. We are also indebted to the general public, who attend in their tens of thousands every year.

For the full announcement, visit the RAF News Website