While cooking the assets of my project, either during packaging or directly via the “Cook content for Windows” menu option, I get a fatal error from UE4. Problem is that there is no hint on why the cooking process fails, none at all (see full error trace at the bottom of this posting).
Here are some facts:
- We are using the official 4.12.4 build (i.e. not the engine sources from GitHub)
- It’s a mixed BP and C++ project
- Happens only with this project (apparently since upgrading to 4.12, but I am not sure about this)
- The problem is reproducible, every time I try to cook
- When I copy the whole project to another machine, then the error happens there as well
- The same goes for our build server, which automatically fetches latest SVN changes
- When I revert back to the last working version from our SVN server, then it works fine again
- Later, when I do some modifications in one or more (BP) assets, then the error comes again
- I tried to delete “Intermediate” and “Build” folders, but still the same error
What bugs me most ist that in some cases, after reverting back to a previous version from SVN that worked, I can carefully make only a small modification in one single BP asset, and then it still works (i.e. no cooking error). However, as soon as I do some more modfications, or change a couple of BP assets, then the cooking errors comes again.
We are trying to solve this issue since many days now, but without success. I am kinda desperate – shipping date is approaching soon, but I have no clue what else I could do. Feel totally lost here 
I am grateful for any ideas you can share.
Thanks in advance for your help!
Here is the full cooking trace:
(The log file mentioned in this trace is basically the same, again without reason for the error)
MainFrameActions: Packaging (Windows (64-bit)): Project.Cook: Cleaning cooked data.
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.RunCommandlet: Running UE4Editor Cook for project M:\Unreal\Projects\GlowRedux\GlowRedux.uproject
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.RunCommandlet: Commandlet log file is M:\Programs\Epic Games\4.12\Engine\Programs\AutomationTool\Saved\Cook-2016.07.01-01.39.46.txt
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.Run: Run: M:\Programs\Epic Games\4.12\Engine\Binaries\Win64\UE4Editor-Cmd.exe M:\Unreal\Projects\GlowRedux\GlowRedux.uproject -run=Cook -TargetPlatform=WindowsNoEditor -fileopenlog -unversioned -cookall -abslog="M:\Programs\Epic
MainFrameActions: Packaging (Windows (64-bit)): Games\4.12\Engine\Programs\AutomationTool\Saved\Cook-2016.07.01-01.39.46.txt" -stdout -FORCELOGFLUSH -CrashForUAT -unattended -UTF8Output
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: LogInit:Display: Running engine for game: GlowRedux
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: LogInit:Display: RandInit(-1199990203) SRandInit(-1199990201).
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.47:783] 0]LogShaderCompilers:Display: Using Local Shader Compiler.
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.48:324] 0]LogDerivedDataCache:Display: Max Cache Size: 512 MB
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.48:402] 0]LogDerivedDataCache:Display: Loaded Boot cache: M:/Users/mfb/AppData/Local/UnrealEngine/4.12/DerivedDataCache/Boot.ddc
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.48:423] 0]LogDerivedDataCache:Display: Pak cache opened for reading ../../../Engine/DerivedDataCache/Compressed.ddp.
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:061] 0]LogTemp:Display: Loaded TP AllDesktopTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:072] 0]LogTemp:Display: Loaded TP WindowsClientTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:085] 0]LogTemp:Display: Loaded TP WindowsNoEditorTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:096] 0]LogTemp:Display: Loaded TP WindowsServerTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:107] 0]LogTemp:Display: Loaded TP WindowsTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:119] 0]LogTemp:Display: Loaded TP AndroidTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:130] 0]LogTemp:Display: Loaded TP Android_ASTCTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:140] 0]LogTemp:Display: Loaded TP Android_ATCTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:153] 0]LogTemp:Display: Loaded TP Android_DXTTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:164] 0]LogTemp:Display: Loaded TP Android_ETC1TargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:176] 0]LogTemp:Display: Loaded TP Android_ETC2TargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:197] 0]LogTemp:Display: Loaded TP Android_MultiTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:197] 0]LogTemp:Display: Loaded TP Android_PVRTCTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:198] 0]LogTemp:Display: Loaded TP HTML5TargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:221] 0]LogTemp:Display: Loaded TP IOSTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:229] 0]LogTemp:Display: Loaded TP TVOSTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:239] 0]LogTemp:Display: Loaded TP LinuxNoEditorTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:250] 0]LogTemp:Display: Loaded TP LinuxServerTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:263] 0]LogTemp:Display: Loaded TP LinuxTargetPlatform
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.49:263] 0]LogTargetPlatformManager:Display: Building Assets For WindowsNoEditor
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.50:205] 0]LogOutputDevice:Error:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: begin: stack for UAT
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.50:205] 0]LogWindows:Error: === Critical error: ===
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: Fatal error!
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2016.06.30-23.39.50:205] 0]LogOutputDevice:Error:
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: end: stack for UAT
MainFrameActions: Packaging (Windows (64-bit)): CommandUtils.Run: Run: Took 14,6046904s to run UE4Editor-Cmd.exe, ExitCode=3
MainFrameActions: Packaging (Windows (64-bit)): Project.Cook: Cook failed. Deleting cooked data.
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: ERROR: AutomationTool terminated with exception: AutomationTool.AutomationException: Cook failed. ---> AutomationTool.AutomationException: BUILD FAILED: Failed while running Cook for M:\Unreal\Projects\GlowRedux\GlowRedux.uprojec
MainFrameActions: Packaging (Windows (64-bit)): t; see log M:\Users\mfb\AppData\Roaming\Unreal Engine\AutomationTool\Logs\M+Programs+Epic+Games+4.12\Cook-2016.07.01-01.40.00.txt
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.CommandUtils.RunCommandlet(FileReference ProjectName, String UE4Exe, String Commandlet, String Parameters)
MainFrameActions: Packaging (Windows (64-bit)): at Project.Cook(ProjectParams Params)
MainFrameActions: Packaging (Windows (64-bit)): --- End of inner exception stack trace ---
MainFrameActions: Packaging (Windows (64-bit)): at Project.Cook(ProjectParams Params)
MainFrameActions: Packaging (Windows (64-bit)): at BuildCookRun.DoBuildCookRun(ProjectParams Params)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.BuildCommand.Execute()
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Automation.Execute(List`1 CommandsToExecute, CaselessDictionary`1 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(Func`2 Main, Object Param)
MainFrameActions: Packaging (Windows (64-bit)): at AutomationTool.Program.Main()
MainFrameActions: Packaging (Windows (64-bit)): Program.Main: AutomationTool exiting with ExitCode=25 (Error_UnknownCookFailure)
MainFrameActions: Packaging (Windows (64-bit)): Domain_ProcessExit
MainFrameActions: Packaging (Windows (64-bit)): copying UAT log files...
MainFrameActions: Packaging (Windows (64-bit)): BUILD FAILED
PackagingResults:Error: Error Unknown Cook Failure