UE4 Crashes when build Lighting

Hi Epic, I have updated my 4.6 preview to 4.6 and now every time I hit build lighting the Editor freezes and does not respond at all. the screen sits on build lighting that is in the drop down list in editor and I have to go to the Task manager to end the process. Most programs say program isn’t responding and wait. but this just closes. and I am not building lighting for a large level. plus because of some of it is a track and doesn’t need to have cast shadows on I have turned it off. below is my mesh in wireframe and as you can see it isn’t that large.

the track is done with splines so that is also why I have turned cast shadows off.

If you are I have some follow up questions:

  • Can you provide your DxDiag? (Start Menu > Run > DxDiag > save text file and upload here
  • Can you tell me if you’re using a Lightmass Importance Volume around your playable area? If not, please place one around your mesh
  • When you hit build lighting, in the task manager in the bottom right there is a small icon labeled “Swarm Agent.” Open this and you should see three tabs. It should be on Swarm status and showing the progress bar for the lights building. YOu should see some movement on this. If unsure you can use the middle mouse button to zoom in on the progress bar. Also check the Log tab and should see some progress here as well. It may not be that it’s freezing or not responding, but instead that it’s taking time to process. This can be greatly affected by your system specs and RAM.

Thank you!


I fixed the problem, I un-installed the 4.6 version and re-downloaded it and re=installed. which fixed the problem. I’m thinking that the first download didn’t download and installed the engine properly. It has happened to me before with other programs. so you can put solved on this. Thanks

Thank you for letting me know! :slight_smile:

I’m glad everything is working as intended now.