[Error] "Maps need lighting rebuilt."

Hello, just calling in to ask about a minor problem.

So, I just went and added the inestimable @'s Foliage Starter Kit to a project – it’s great – but when I set my directional light to stationary and go to build the lighting, I get this in my message log:

WorldInfo_0 Maps need lighting rebuilt

And the lighting looks terrible. I’ve switched my light to movable and things look much better, but I hear movable lights eat up a lot of performance in larger levels. I’m not keen on that.

So, is this a common error? I did not get it before using the Foliage Kit, but @ assures me there’s probably something else going on. Any help is appreciated.

-A solution could be that you move your map + assets into a new project :slight_smile:
-which engine version do you use?

Whenever you have an actor that is set to cast static shadows, you will need to rebuild lighting for stationary lights. Do you have a lightmass importance volume? Also, as asked, which version are you using? It seems there might have been a similar issue with 4.3 - https://answers.unrealengine/questions/72390/bug-worldinfo-0-needs-rebuilt-lighting-but-ive-don.html

Using 4.7.2, and I do have a lightmass importance volume set up. I could try moving everything into a new project, but doesn’t that seem like an unsustainable solution?

I know that it’s not the best solution, but I read that it could might solve the problem -> because there are just two thread with the same topic around and all of them solve the problem with using a new project :slight_smile:

Ack! You know what I did? Simply restarted Unreal. When I switched to stationary and rebuilt the lighting it went fine.

Oh well. Sorry for making a mountain out of a molehill. Thanks for all the advice.

Hi everyone, I started having this problem as I was adding foliage. I thought that if I reduced its lightmap to 8 (instead of 128) would help but it doesnt.
As it appears, the only solution is to move my map and assets to a different level/project?

Could someone explain to me how to do that? It took me a looong time to build everything :frowning:
What is the relationship between Project-Level-Maps? I thought the later two were the same but apparently they arent?

Thanks in advanced for the help!

Hi again,
I migrated all the assets to a new project but eventually the error came up again. After messing around with the engine, I found that I had another map using the same assets/textures so i deleted it (just in case) and it seems that it worked… Now im able to build everything again and no error.

Every time I open the editor I in this phantom level (which has nothing on it) so i move to my custom level and decide not to save that old one. Is there any way of seeing ALL the levels/maps inside the same project, so that i can delete the unwanted ones?


I had suffered this problem from foliage, InstancedStaticMeshComponents as well.
However have found a solution to fix it in 4.7.6.

  1. Open ‘World Settings’.
  2. Goto ‘Lightmass’ category.
  3. Check ‘Force No Precomputed Lighting’.
  4. A popup will appear. Press ‘OK’.
  5. Press ‘Build All’ or ‘Build Lighting Only’. Static Lighting will be crack. That’s OK.
  6. Save the map.
  7. Reload the map. Open another map and open the map or double click the map in content browser.
  8. Lightmaps will be 0 in Lightmass categoty. If not, load the map again.
  9. Uncheck ‘Force No Precomputed Lighting’.
  10. Save the map.
  11. Press ‘Build All’ or ‘Build Lighting Only’.
  12. Solved. :smiley:

Worked great! thanks much!!!

, you are a saint. This just got me out of a MAJOR bind. Thank you.

!! You are amazing. Thank you !

its stupid perhaps but since i’m new to unity i’m having problems with your point

  1. Save the map.
  2. Reload the map. Open another map and open the map or double click the map in content browser.

how and where do i save a map. what is a map. i’m almost there… please help

This worked!

Hi Can you pls explain how to do 6. 7. 8. PLS PLS PLS !!! IT IS URGENT !!!

I ran into this problem. Very frustrating. I had to delete all the foliage in order to solve this “light needs to be rebuild” issue. I did not need to delete other maps or restart the map again.
My Project is an open outdoor mall and it has a huge world. Highway, entrance, parking and 40 warehouses. Very extended.
I am using stationary lights (both directional and skylight are stationary).
I left some trees tough, but they were placed as mesh in the scene and not as foliage.
I fear if I redo the foliage again, I will run into the same problem.
Any suggestions please?
Is it a good idea to set the foliage as “movable” and enable modulated shadows in the directional light?

It works!Thank u

I just rebuilt unreallightmass in VS and sorted

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what do you mean moved to stationary? im having same problem

this works but with this method my huge forest with some foliages does not cast shadows anymore!