1.6.12 board manager troubleshooting

Hi!

I'm a student learning how to work with arduino 101 on mac. I wanted to install 101 via the board manager but i got the error "error downloading http://downloads.arduino.cc/packages/package_index.json"

I tried reinstalling, restarting and searched on the web but couldn't find something.

Your computer needs to be connected to the internet to install support for the 101 using Boards Manager. You may also need to set your firewall to allow the Arduino IDE access to the internet.