Boards manager 0.0.4-rc1 issues

Hi im trying to update my arduino environment but when i run update from board manager for ver 0.0.4-rc1 it says"CRC doesnt match,File is corrupted maybe temporary problem please try later
ive been trying all day any ideas
running arduino 1.8.10
was hoping to sort problem with AsyncTCP throwing errors when trying to compile
cheers
Pete