Frage: MacOS Sierra is NOT available on the AppStore!
just thought i'll upgrade to Sierra after finishing a development project. No what? Sierra is not available on the App Store for whatever reason. And High Sierra is not an Option right know if you have a good customized tool setup.
I run a MacBook Pro (Retina, 15', Mid 2015), so i would expect no issues.
Any information from @Apple why Sierra can't be installed?