It seems you have this error:
LogPackageName:Error: DoesPackageExist: DoesPackageExist FAILED: ‘None’ is not a standard unreal filename or a long path name. Reason: Path should start with a '/'
From what I have seen in another AnswerHub thread, this could be related to the GameMode being set to None. Try go to Project Settings / Maps and Modes / Default Modes, then set Default Game Mode and Global Default Server Game Mode (under the arrow) to any other game mode than none.
Try build again after that. It is a long shot, but hopefully it is just this.