Macbook Air, mid 2013 wont upgrade past 10.8.5
I have bought a used macbook air off my boyfriends sister, she never used it so it has not been touched for a while. I wiped everything off that she had but the OS is stuck at OS X Mountain Lion and every time I try to upgrade to a new OS it gives an error message. Is there a direct link that I can use to upgrade to the next OS? I'm stuck not sure what to do.
MacBook Air