Incorrect lighting after traveling to level in windowed fullscreen mode

Hey guys. This one is kind of weird. It’s been present in my project for a while, but it’s next on my list of things I need to fix, so I’m opening a bug report for it because I’m starting to think it’s an engine bug. I haven’t been able to isolate it or find the cause of the problem – but more on that in a bit, after I explain the problem itself.

What happens is this: whenever traveling to a level with the windowing mode set to windowed fullscreen (EWindowMode::WindowedFullscreen), the lighting is wrong. It looks like the direct contribution from the directional light is wrong, and the skylight is wrong, and maybe other stuff? It’s hard to say exactly what’s going on. But it’s clearly wrong.

This problem does not occur if the windowing mode is changed while already in a level. Example, a map is already in progress, and the player switches from Windowed to WindowedFullscreen – it’s fine. But, if the player sets the window mode to WindowedFullscreen on the title screen, and then travels to a new level, the problem will occur. It will also occur when traveling back to the title screen level, or if the game’s windowing mode is already set to WindowedFullscreen and the game is started.

The problem does not go away if the windowing mode is changed from WindowedFullscreen to Windowed or Fullscreen if the level was loaded while the windowing mode was WindowedFullscreen – it will remain messed up until another level is loaded with the windowing mode set to something other than WindowedFullscreen.

This problem occurs both with packaged+cooked content, and with uncooked (editor with -game). It seems to happen both with seamless traveling and without.

It’s entirely possible I’ve misconfigured something in my project. However, I’m not seeing any warnings or errors in the logs, and I don’t know how to begin isolating this or troubleshooting the problem any further.

I’m using baked lighting, with a single stationary directional light per level and stationary skylights. DFAO and mesh distance fields are not enabled, LPVs/dynamic GI are not enabled. Lightmass volumes and samples are working correctly, map check shows no problems. I can provide the project files if anyone at Epic would need them to help figure this out, or I can try to construct a small standalone example project that demonstrates the problem in isolation if you think that will help. I’m not really sure where to start with figuring this out.

I’m attaching 3 screenshots, each showing the results after loading a map with a different windowing mode: Windowed, Fullscreen, and Windowed Fullscreen.

Hi cancel -

I was able to reproduce this issue internally and have entered a bug report as UE-25624. As we continue to investigate this issue and work toward a solution I will keep you informed here.

Thank you -

Eric Ketchum

Any news on the bug? We are having the same problem since months.

Hey there,

are there any news about this problem?



There is no update at this time.

Can you tell how long it takes? It’s really annoying and you just can’t ship a game with this bug.


There is no set time for bugs that are entered. The teams that they are assigned to set the priorities and plan accordingly. It’s currently marked as “To Do” and not backlogged, but it’s just dependent on a number of other priorities that need to be addressed first. Sorry for the inconvenience.

If you are a programmer and make the fix yourself you can always submit the pull request via GitHub referencing the JIRA number so that the fix can be integrated as well.

For any future Googlers or anyone needing to know, this bug has been fixed (or at least no longer appears for me) in 4.12.