Lighting Build failed. Swarm Failed to kick off

Hi guys,

I’ve been getting this error: “Lighting Build Failed. Swarm Failed to kick off.”

I’ve been getting it for about a month now.

I’ve tried everything to fix it. Unsuccessfully, I have tried everything from loads of Google search results, like:

  • Clearing Cache
  • Renaming Meshes with duplicate names
  • Removing Lighting completely and trying to build
  • Copy/Paste into new level
  • Manually running Swarm (Gives me Connection error)
  • Deleting hundreds of meshes and trying to build
  • Removing reflection captures
  • Removed NULL actors, no luck

I can build lighting in a new, empty level, it is just this level that is having the problem.

Could anyone help?

If anyone could point me in the right direction I will provide logs. ( I do not have a folder called “Swarm” inside “4.10\Engine\Saved”

Thank you

Do you have any virus protection software that may be hindering it? Try to put your virus protection in Gaming Mode or disable it for the time being.

There’s also a chance that your map is corrupted.

Try this: Go to File > Export > save a .t3d file > Create a new map > File > Import > and select the .t3d file you just created.

Lastly, if none of those work: Delete sections/assets of the map and place them back on the map, so you are going to essentially rebuild the level, piece by piece. Keep track of what assets finally enable you to rebuild the map after deleting/replacing them just in case you have the same issue in the future.

I have tried disabling my antivirus and have now removed it too. Nothing works.

Importing the t3d file did not work.

I’ve already tried it but I will try deleting sections of the map again. I have thousands of assets so this will not be fun!

I’ll update you

Ok so if I delete everything… It works. If I go through and delete everything part by part, it doesn’t work. (So, everything beginning with A gets deleted. Build… Error. Everything with B… .etc.)

Any help?

Have you tried to migrate the level to a new project?

Do you mean Migrate the Assets? How do I migrate the whole project so everything is exactly how it should be in the map? haha