This may sound stupid, but are you using any BP_SkySphere or something that uses it as a parent class (such as UltraDynamicSky)
I was able to get a build to happen after deleting that and re-adding it to the map.
Note: That the BP_SkySphere did not need to be in the level with the child actors
I am using bp_skysphere, and I will test deleting it (im formatting my dev machine atm as a test) however I dont think thats the issue as I’ve been able to cook and package my game with the skysphere in it.
How did you isolate the sphere as a issue? was it a linker warning in your cook logs? because I have a lot of those and I had a lot of them in 4.10 as well and it doesn’t affect anything
I couldn’t get the child actor problem to appear in a blank project, but it would appear if I included the starter content. If I deleted the starter content out, the error would disappear. Then I narrowed it down to the “Starter Map” and started deleting things out of it until magic happened. It may not be the end-all to the problem. But it seems to work for me.
Also, w/o child actors, the BP_Skysphere would not throw any errors. Again it didn’t matter if the BP_Skysphere was on the map that the child actor issue was, which is really, really strange.
I wish you the best of luck.
edit: This did not solve our issue for our big project, we’re still trying to figure it out. Good luck
I formatted my dev machine and did a clean install with latest from 4.11 from git - same cook issue. So I think that eliminates any more “residual stuff from other 4.10 tools” cases.
Hey BPANDREW,
So the initial assertion that’s provided in your crash report seems to be one that is included in a broad amount of crashes.
Could you create a new project and migrate your files over to the new project and then package the game and let me know whether or not you still run into this issue?
Make sure you’re not overriding your original project, and that you’re working with a copy of your project when migrating.
Feel free to PM me with the new logs.
Also, if you know any reproduction steps to cause this crash to occur, could you please list those to us for further investigation?
By the way, I noticed that you’re on 4.11.2 in our main branch. Honestly, 4.11.2 isn’t released yet so there are likely bugs that haven’t been caught by QA or fixed by our Developers. Just a heads up, because that could be what’s causing the issue you’re currently seeing.
Thanks! 
I’ve sent you a note on the forum with a url to my new cook file - I’m sifting through it - it doesnt have THIS failure but it fails due to a bunch of errors. My child objects dont seem to work correctly.
This also gave me the idea of taking the config directory of a new project and open my broken project (to see if perhaps it was a legacy config issue) - sadly that didn’t help at all
comparing my broken cook to my one that “works” in the new project - this seems to be the next thing to execute that doesnt
MainFrameActions: Cooking (Windows): UE4Editor-Cmd: [2016.04.13-21.27.59:516][ 0]LogTexture:Display: Building textures: T_Castle_ThumbstickInner (BGRA8)
MainFrameActions: Cooking (Windows): UE4Editor-Cmd: [2016.04.13-21.27.59:517][ 0]LogCook:Display: Cooking /Engine/MobileResources/HUD/T_Castle_ThumbstickInner → C:/Users/andrew/Documents/Unreal Projects/MyProject/Engine/Content/MobileResources/HUD/T_Castle_Thumb
MainFrameActions: Cooking (Windows): stickInner.uasset
Pulled from 4.11 git this morning - game cooks :D:D:D:D:D:D
BPANDREW, what was your final solution to this? I am also on 4.11.2 and worrking through this same error.
NM. see it below. trying.
Hi and BPANDREW, what was your final solution? We are having this error as well. I noticed mxnko said that they see the solution below, but we are unable to see it.
Hope you may shed some light. Thank you in advance!