[Bug report] Light wont build in 4.9 without a SM_Template_Map_Floor

This sounds weird, but when I can’t build light on a level if there isn’t any SM_Template_Map_Floor. It will just stuck in 50% (or 80%, depends). Here are the steps I followed:

  • Create a new project
  • Create an Empty Map
  • Add a cube and some point lights
  • Build Lighting : It gets stuck on 50%
  • Add a SM_Template_Map_Floor with any material
  • Build Lighting: It works like a charm

Note: the mesh can be in any part of the world, even incredibly far. It just makes it work

Any explanation for this? Is my computer or a real bug? Anyway, thanks in advance!

Hey Mago314,

Would you mind providing me with some reproducible steps in a new blueprint project so I can see what you are reporting?

Be sure you have added a lightmass importance volume to your scene to help your scene build lighting a bit more efficiently.

I wish I had an explanation at the time to tell you what could be happening, but this issue sounds very unique so I am curious to see if I can reproduce this on my end as well.

Would you also mind providing me with your ‘dxdiag’ so I can take a look at your computers specifications?

Thank you,

@Mago314 Simple as 1) Create new mobile game, no starter content, 2) Try to build, there you go, stuck forever building lights

I started feeling desperate as I found this bug too. I too found out that adding that starter content mesh would allow to build lights, without it simply stays stuck.

Hey all,

I was able to test this issue and can confirm this report. I went ahead and entered a bug for this issue (UE-20782).

When a fix for this issue has been implemented it will be added to the release notes of an upcoming hotfix or full release. You can find the Release Notes on our Documentation or the Forums under the Announcements and Releases section.

Thank you,

I was able to get around this issue by adding any BSP brush. The sm template map floor is also a bsp mesh converted.