Building Lighting in 4.9 never completes (repro case/move)

My previous bug report on this matter was “accepted” so I think a new report that’s actually open would be best.

I have reproduced the problem where building lighting never finishes in 4.9. It seems that this happens for scenes that have no BSP geometry. The default scene, delete the default floor, has this problem. Add a static mesh cube, it still has this problem. Delete the static mesh cube, add a BSP block cube, and it works again.

I have made a 2-minute mp4 video demonstrating this on a fresh 4.9 with a fresh empty project:
(the 5 MB forum attachment limit is exceeded, so get it from here:)

Here is the previous report:
I’ve also attached my DxDiag.txt file here to this post.
link text

Also, another hint: If I change the size of the BSP cube to 5x5x5 cm, then lighting build never finishes. 200x200x100 works fine. So it’s possible the problem with the static cube is the size of it, not the fact that it’s static.

The reason this matters to me is that I have some levels that have no geometry, just UMG user interfaces. Those never finish building. The work-around is to stick some black BSP geometry somewhere, I guess, but it’d be nice if this just wasn’t a problem!

I’m going to close this post as a “Duplicate/Addition” to the other report you’ve already submitted that I’m assigned to.

Why does Build stop at 50% lighting - Platform & Builds - Epic Developer Community Forums

In instances like this where the issues are part of the same problem please post them to the original post.

As for the ticket being “accepted” this happens anytime a staff member makes a comment or and answer. The ticket will be marked as accepted. It is setup this way so that we can easily see when question has been re- opened by the OP or another user with additional information or seeking an update to a reported bug.

I’m going to link this information to the other post as well.