Screenshot of error
I am running [ Android Studio 2.3 Build #AI-162.3764568, built on February 24, 2017 JRE: 1.8.0_112-release-b06 amd64
I was facing the same problem, I solved it by first enabling the "Force https://... sources to be fetched using http://..." setting in the SDK Manager Tools > Options menu. and then I opened Android Studio as administrator.