One things I’ve noticed after Fresh Installing /updating my Hackintosh my App Store would not let me sign in any more.After reading various apple /non forum posts and deleting plist files but still caches, nothing works for me Then I came across a post that suggested that the problem could be with the Ethernet controller
Do the following Steps to solve this problem :
1:-Download EFI studio and chameleon wizard
2:-Open EFI studio
3:-Click on Select Device and choose Ethernet and Click Add Device
4:-Copy HexString and open Org.Chameleon.Boot.Plist and
160000006200750069006c0074002d0069006e0000000500000001
5:-Repair Permissions using kext utility and reboot your Apps store should work