Problems packaging game! Demo is almost ready to ship, please help!

I’m having a very difficult time packaging my game. I’ve been working on it for some time and the demo is about ready to deploy.

Having said that, I have already :

-migrated all my assets/preferences to an empty project
-installed the SDKs needed
-test-played my demo, and it works; no map errors, only warnings

Here is the last bit of output when I run a build :

Cook: Execution of commandlet took: 1232.51 seconds
Cook: LogOnline: Display: Unloading online subsystem: NULL
CommandUtils.Run: Run: Took 1253.7393806s to run UE4Editor-Cmd.exe, ExitCode=1
Project.Cook: Cook failed. Deleting cooked data.
Program.Main: ERROR: AutomationTool terminated with exception: AutomationTool.AutomationException: Cook failed. —> AutomationTool.CommandletException: BUILD FAILED: Failed while running Cook for D:\LiveNightmares_Storage\Assets\Unreal\4.17\LivingNightmares\LivingNightmares.uproject; see log C:\Users\Ed\AppData\Roaming\Unreal Engine\AutomationTool\Logs\D+Unreal+UE_4.17\Cook-2017.12.02-13.31.24.txt
at AutomationTool.CommandUtils.RunCommandlet(FileReference ProjectName, String UE4Exe, String Commandlet, String Parameters)
at AutomationTool.CommandUtils.CookCommandlet(FileReference ProjectName, String UE4Exe, String[] Maps, String[] Dirs, String InternationalizationPreset, String[] CulturesToCook, String TargetPlatform, String Parameters)
at Project.Cook(ProjectParams Params)
— End of inner exception stack trace —
at Project.Cook(ProjectParams Params)
at BuildCookRun.DoBuildCookRun(ProjectParams Params)
at BuildCookRun.ExecuteBuild()
at AutomationTool.BuildCommand.Execute()
at AutomationTool.Automation.Execute(List1 CommandsToExecute, Dictionary2 Commands)
at AutomationTool.Automation.Process(String[] Arguments)
at AutomationTool.Program.MainProc(Object Param)
at AutomationTool.InternalUtils.RunSingleInstance(Func`2 Main, Object Param)
at AutomationTool.Program.Main()
Program.Main: AutomationTool exiting with ExitCode=25 (Error_UnknownCookFailure)
BUILD FAILED

Please help, I’m ready to distribute my game to my testers!

Thank you for your time!!!