I am using Android SDK Manager revision 23.0.5. I tried to update some SDK, but got this errors. I tried a lot of times. And I try to use \"https://\" in the option but failed.
Clearing the SDK Manager cache: [Tools > Options > Clear] Cache and the reloading [Package > Reload] helps.
Also in some cases disabling the real time protection of your anti virus or the whole anti virus may solve the problem.
Finally a guess may be that forcing to use http for downloading repos may solve some problems [Tools > Options > Force https sources to be downloaded using http].