Summary
For the past few days, I’ve been having an issue launching a session through UEFN on one of my maps.
When the project loads in Fortnite, I see an ERROR message, and in UEFN, I encounter problems that prevent the session from starting.
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Assets
Steps to Reproduce
Steps to Reproduce:
Open the project in UEFN.
Click “Launch Session.”
Wait for the session to start.
Notice that the session fails to load in Fortnite and an ERROR message appears.
In UEFN, check the message log – Platform Cook errors are shown.
The issue might be related to imported custom assets (e.g. textures or meshes), which could be causing validation or cooking failures.
Expected Result
Open the project in UEFN.
Wait for the initial loading process to complete.
Click “Start Session” to launch the project in Fortnite.
Observe the error that appears in Fortnite (ERROR message).
Check the UEFN message log – it shows cooking/validation errors.
Note: The issue may be related to imported assets/textures in the project.
Observed Result
When trying to start a session, an “ERROR” message appears in Fortnite.
In UEFN, the Message Log shows multiple PlatformCook and asset validation errors.
The session does not start, and I cannot test or publish the map. This is note form message log after that:
We hit an error while cooking this content
errors.com.epicgames.content-service.cook_failure
CookJobId:d784cd37-fd7d-4ed6-8b3f-0080151926ec
An error occurred while communicating with the game servers (failed to cook module 7c1b9afd-42c6-cc98-f44c-38978996dbe4 (artifact e9121755-b71c-423d-a44d-8710e4159b1b:linux-server) (cookJobId d784cd37-fd7d-4ed6-8b3f-0080151926ec) with error code errors.com.epicgames.cookplugin.assetvalidationerror).
Platform(s)
windows
Island Code
8135-8336-8668
Upload an image
Video
Additional Notes
this problem appeared when I was preparing a new update for the map and then importing many files to UEFN