Download failed

Hi,

when I tried to update to wordpress 4.2.2. I recive this message
“Downloading update from https://downloads.wordpress.org/release/wordpress-4.2.2-partial-1.zip…
Download failed.
Installation Failed”

and also when updating the theme also failed with message
“Updating Theme Twenty Fifteen (1/1)
Downloading update from https://downloads.wordpress.org/theme/twentyfifteen.1.2.zip…
An error occurred while updating Twenty Fifteen: Download failed.”

What should I do?