Error Unknown Cook Failure, after upgrading to 4.10.1

MainFrameActions: Packaging (Windows (64-bit)): BUILD FAILED
PackagingResults:Error: Error Unknown Cook Failure
(Win 64bit Development Build)

I updated from 4.9 to 4.10.1, first using the github build but I recived this error and switched to the binary build from the launcher, however returning the exact same problem. The project will not get packaged. No other errors are present. (exept for a stack in the middle of the build, but its always been there and cause no issues)

If I create a new project in 4.10, empty project, no starter content, it will package and build correctly with no errors.
I have tried refreshing nodes and recompiled most blueprints, restarted this, restarted that and reinstalled visual studio 2015 a few times to no avail.

The project was converted in place using the UE4 project screen, but Ive also tried to right click on the project file, change engine version, generate project files, and refreshed project files from editor with no different results.

Any help is appreciated!
dropbox link to build log file:
https://dl.dropboxusercontent.com/u/100247879/log.txt

So, after a sleep-less night and morning I’ve gone through a process of elimination to find the source of the problem.
The build fail is caused by project content/assets. After a lot of trail and error I’ve found the assets causing the packaging to fail. Specificly the blueprint and child blueprints from the Horror Pack from the marketplace.
I have no idea why, they are simple blueprints and give no errors or warnings when compiling or running them in the game inside the editor, but packaging the project with these assets in a map will cause the build to fail.

No other blueprints cause these issues so far.

The blueprints folder is spelt “bluprints” I was getting the same unknown error until I changed the spelling to the correct spelling and this fixed the problem I hope it fixes the problem for you too.

Hi there,

I´m working on a project and I have the same issue after downloaded the Horror Pack.

@GearSunBro, thanks. That worked for me :slight_smile:

@CaptnC001

Sorry only just seen your reply, glad this worked for you too :slight_smile: