I get that error message and can’t package my project its for android etc1 i read the other questions they have a solutioun for this problem an its : Switch the configuration of UE4.sln from “Development Editor” to “Development” and recompile, your problem will be solved. The configuration is “Development Editor” by default, and it includes only the editor." but the problem is in my computer there is no ue4.sln or GenerateProjectFiles all i have is thesee ara so please help me to solve this problem its my fist game after all 
they are talking about havig the game built in visual studio from raw cpp source from github. then you get an engine.sln and a generateprojectfiles.bat
lookat UnrealEngine · GitHub or whatever the link it, its in your profile on the main unrealengine.com page
I did what you said and find it but GenerateProjectFiles error - AnswerHub - Unreal Engine Forums this problem happened