BUILD FAILED: Failed while running Cook

Hello, i am getting this Error when i try to compile my project. Please note that this issue is recent as i was able to package this project last week.
Changes i have made this week are:

  • I have replaced 2 assets from the store with assets provided from the creator as the 2 from the store were broken.
  • I have changed the Navmesh - Generation - Cell Size = 5 / and Agent Radius 1

These are the only 2 major changes i have made as the rest of the work has been mostly level desing.

Log:

MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2015.08.16-12.22.06:628][ 0]LogExit: Executing StaticShutdownAfterError
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.Run: Run: Took 605.260619s to run UE4Editor-Cmd.exe, ExitCode=-1073741819
MainFrameActions: Packaging (Windows (64-bit)): InternalUtils.SafeCopyFile: SafeCopyFile C:\Program Files\Epic Games\4.8\Engine\Programs\AutomationTool\Saved\Cook.2.txt C:\Users\Mankind\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+4.8\Cook.txt
MainFrameActions: Packaging (Windows (64-bit)): InternalUtils.SafeDeleteFile: SafeDeleteFile C:\Program Files\Epic Games\4.8\Engine\Programs\AutomationTool\Saved\Cook.2.txt
MainFrameActions: Packaging (Windows (64-bit)): Project.Cook: Cook failed. Deleting cooked data.
MainFrameActions: Packaging (Windows (64-bit)): ErrorReporter.Error: ERROR: AutomationTool error: Cook failed.
MainFrameActions: Packaging (Windows (64-bit)): BuildCommand.Execute: ERROR: BUILD FAILED
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: ERROR: AutomationTool terminated with exception:
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: ERROR: Exception in AutomationScripts.Automation: BUILD FAILED: Failed while running Cook for C:\Users\Mankind\Documents\Unreal Projects\ProjectMaze\ProjectMaze.uproject; see log C:\Users\Mankind\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+4.8\Cook.txt
MainFrameActions: Packaging (Windows (64-bit)): Stacktrace: at Project.Cook(ProjectParams Params)
MainFrameActions: Packaging (Windows (64-bit)): at BuildCookRun.DoBuildCookRun(ProjectParams Params)
MainFrameActions: Packaging (Windows (64-bit)): at BuildCommand.Execute()
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Automation.Execute(List1 CommandsToExecute, CaselessDictionary1 Commands)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Automation.Process(String[] CommandLine)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Program.MainProc(Object Param)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.InternalUtils.RunSingleInstance(MainProc Main, Object Param)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Program.Main()
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: ERROR: BUILD FAILED: Failed while running Cook for C:\Users\Mankind\Documents\Unreal Projects\ProjectMaze\ProjectMaze.uproject; see log C:\Users\Mankind\AppData\Roaming\Unreal Engine\AutomationTool\Logs\C+Program+Files+Epic+Games+4.8\Cook.txt
MainFrameActions: Packaging (Windows (64-bit)): ProcessManager.KillAll: Trying to kill 0 spawned processes.
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: AutomationTool exiting with ExitCode=25
MainFrameActions: Packaging (Windows (64-bit)): Domain_ProcessExit
MainFrameActions: Packaging (Windows (64-bit)): ProcessManager.KillAll: Trying to kill 0 spawned processes.
MainFrameActions: Packaging (Windows (64-bit)): copying UAT log files…
MainFrameActions: Packaging (Windows (64-bit)): RunUAT.bat ERROR: AutomationTool was unable to run successfully.
MainFrameActions: Packaging (Windows (64-bit)): BUILD FAILED
LogD3D11RHI: InitD3DDevice
LogD3D11RHI: InitD3DDevice