Light rebuild stop at 0%

I’m rebuilding lighting. But it stop at 0%. I follow the step in the site. But it doesn’t work.

Hello wukakuki,

I have a couple of questions that should help narrow down where the issue is.

1.) Is this build from a copied project from an older version of the engine to 4.9?
2.) Can you reproduce this in a new blank project?
3.) Does it actually stop or does it take a really long time to get to 1%?
4.) Can you link me your DxDiag?

After I have this information I will continue to investigate this issue and hopefully pinpoint the problem.

Thank you,

I build from the template in 4.9, and just change the matrial of the floor and the wall.
I just create a new blank project. Build the light. And then, stop at 0% again.
I had waited a day and a night. 0%. Not go to 1%.
I use mac. No directX support.
OS 10.11.1 (15B17c)
2.8 GHz Intel Core i7
16 GB 1600 MHz DDR3
Intel HD Graphics 4000 / NVIDIA GeForce GT 650M

Hello wukakuki,

There is a few things that could be causing this issue. Please check to see if your Intel Card is switching off and the Nvidia Card is running.

1.) Can you test this on 10.10?

If the card is working as intended and it does still occur in 10.10 then this could possibly be an engine issue. If lighting builds in 10.10 and not 10.11 then this could be a beta specific issue with Capitan.

Please let me know the answers to these questions and I will continue to investigate this issue in the meantime.

My mac has upgraded to 10.11. I don’t have a mac with 10.10. Sorry! Can this be fixed?

Hello wukakuki,

I will be checking to see if we have a make that is currently upgraded or will be upgraded to 10.11.

Hello wukakuki,

We have not currently updated to 10.11 yet. Currently we do not support 10.11. I do not have a date for when that will be. I will keep you posted on when we move to support 10.11

Thank you,

Thank you!

Hello wukakuki,

I apologize. I believe I answered this too quickly. I have a bit more information that I would like to check if this could be a lighting build issue as opposed to an OSX issue.

1.) Is this a github build or one from the Launcher?
2.) Do you see the UnrealLightmass process in your viewport while the lighting is stuck at 0%?
3.) Can you open your swarm agent while building your lighting and notice any change there?
4.) Does this happen in 4.8?
5.) Can you create another blank project and build there?

Thank you,

The one from launcher. I had tried to create a blank project and build light without any change. But stuck at 0%. UnrealLightmass process is working while the lighting is stuck at 0%.4.8 could not compile in OS 10.11. where can I open swarm agent. I can’t find it in unreal engine

Hello wukakuki,

Whenever you build lighting you will notice that it says building status very briefly before the windows come up telling you the percentage of the light build. In the bottom right of your computer screen an icon will appear that’s black and yellow. That is your swarm agent. You can open that and watch the build progress on your machine.

We tested this exact issue on another machine that is using the 10.11 beta and we were able to build lighting. Not too sure what is causing this.

which one? black and yellow icon? Does this means my swarm agent can not start?

Hello wukakuki,

This one in the bottom right of your task bar. Double click on it and keep it open during build.


I use mac. Don’t have task bar

Mac haven’t a task bar. Where I can find swarm agent on my mac?

Hello wukakuki,

I apologize again. Apparently the swarm Agent is a windows specific process and is not loadable on a mac. What you can do is check your processes by looking at your task manager > performance when running a lighting build. That should show whether your cpu is trying to run the lightmass or not.

yep! running. Unreallightmass is running

Hello wukakuki,

I have been able to track this down to a known bug where the lightmass is running but the build hangs at certain percentages. We are currently trying to track this down as this seems to be one of the larger issues with 4.9.1.

The ticket number is UE-20782.

I will keep you posted on this bugs progress. I hope this issue is resolved very soon.

I would recommend trying to build this in 4.8 in the meantime.


@wukakuki When I open VPN met the same question in UE4.9.2, Turn off the VPN, Restart UnrealEditor, It works OK,
Mac OS 10.10
2.5 GHz Intel Core i7 16 GB 1600 MHz DDR3 AMD Radeon R9 M370X 2048 MB

Beijing ni dong de :slight_smile: