# Lighting build failed. Swarm failed to kick off

**URL:** <https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953>\
**Category:** Rendering\
**Tags:** swarm, unreal-engine, crash, editor, Lighting, question\
**Created:** [July 11, 2014, 2:50pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953 "2014-07-11T14:50:55Z")\
**Posts on this page:** 20\
**Page:** 2

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**Author:** ![Valachio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Valachio](https://forums.unrealengine.com/u/Valachio)\
**Post date:** [April 6, 2015, 8:14pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/21 "2015-04-06T20:14:10Z")

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Btw, should I delete the file or rename it? I renamed instead of deleting

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**Author:** ![Valachio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Valachio](https://forums.unrealengine.com/u/Valachio)\
**Post date:** [April 6, 2015, 8:23pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/22 "2015-04-06T20:23:45Z")

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I just through all the meshes in my project and gave each one of them a unique name.

Still the same error.

Also I found some duplicate meshes. I tried deleting them but it wouldn’t let me. Maybe I need to delete these duplicate meshes instead of renaming them?

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**Author:** ![Valachio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Valachio](https://forums.unrealengine.com/u/Valachio)\
**Post date:** [April 7, 2015, 12:10pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/23 "2015-04-07T12:10:26Z")

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Ok so I went through every single one of my meshes (felt like the most pointless ever done lol).

And I still get the same error.

What is happening?

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**Author:** ![devtonstudio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@devtonstudio](https://forums.unrealengine.com/u/devtonstudio)\
**Post date:** [April 7, 2015, 12:10pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/24 "2015-04-07T12:10:34Z")

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for what you copy this same meshes meany times, or make this same names, its not prof. ???, first of all, we told you, what you must do to fix this, its simple, go to work, and clean this mess, its very imprtant to create all project without technical bugs, errors, 400 meshes its a like “Notihng to do” :))), i worked witch one project, where i found more than 10.000 wrong names, now its ok.

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**Author:** ![Valachio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Valachio](https://forums.unrealengine.com/u/Valachio)\
**Post date:** [April 14, 2015, 2:28am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/25 "2015-04-14T02:28:37Z")

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Hey, sorry I did not realize you responded. I corrected all the names of the meshes so each of them have different names now. However I am still getting the same error ☹

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**Author:** ![Valachio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Valachio](https://forums.unrealengine.com/u/Valachio)\
**Post date:** [April 14, 2015, 2:29am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/26 "2015-04-14T02:29:15Z")

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I don’t think the problem is duplicate meshes. Because I can build lighting on a different level in the same project with no issue. It’s only on my main level that I get this error.

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**Author:** ![devtonstudio](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@devtonstudio](https://forums.unrealengine.com/u/devtonstudio)\
**Post date:** [October 2, 2015, 12:33pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/27 "2015-10-02T12:33:13Z")

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one again time i have this same problem, and i solved by rename duplicate names of mesh and materials

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**Author:** ![gmmsv14](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@gmmsv14](https://forums.unrealengine.com/u/gmmsv14)\
**Post date:** [December 5, 2015, 10:57pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/28 "2015-12-05T22:57:24Z")

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I solved that problem by fallowing this post:

> **[Unreal Engine 4.7.3 Lighting build failed. Swarm failed to kick off](https://forums.unrealengine.com/questions/201235/unreal-engine-173-lighting-build-failed-swarm-fail.html)**
>
> Hi, when trying to build my project in Unreal 4 I get a ‘kicking off swarm message’ and then instantly a ‘Lighting build failed. Swarm failed to kick off.’ Here’s some of my output log: LogInit: Version: 4.7.3-2479750+++depot+UE4-Releases+4.7 ...

maybe it will help good luck !

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**Author:** ![Zaggoth](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/zaggoth/32/876721_2.png) [@Zaggoth](https://forums.unrealengine.com/u/Zaggoth)\
**Post date:** [April 26, 2017, 3:41pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/29 "2017-04-26T15:41:56Z")

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Alternative steps that might work for some people: [UE4 Fix – “Lighting build failed. Swarm failed to kick off.” – Zag's Blog](https://zaggoth.wordpress.com/2017/04/26/swarm-failed-to-kick-off/)

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**Author:** ![anonymous\_user\_0df14252](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_0df14252](https://forums.unrealengine.com/u/anonymous_user_0df14252)\
**Post date:** [June 9, 2017, 5:06pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/30 "2017-06-09T17:06:50Z")

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[SOLVED]

I found a way to solve it through code. I wrote this little piece of code here:

```
	TMap<FGuid, UMaterialInterface*> guids;

	for (TObjectIterator<UMaterialInterface> it; it; ++it)
	{
		UMaterialInterface** result = guids.Find(it->GetLightingGuid());

		if (result == nullptr)
		{
			guids.Add(it->GetLightingGuid(), *it);
		}
		else
		{
			it->SetLightingGuid();
			it->Modify();
		}
	}

```

I personally have an editor plugin to do this but I think it could work anywhere in code.  
This actually regenerates the lighting ID that causes the conflict that you see in the swarm agent log.

After that, just save the modified assets and rebuild.

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**Author:** ![jvukovich](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@jvukovich](https://forums.unrealengine.com/u/jvukovich)\
**Post date:** [July 12, 2017, 4:19am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/31 "2017-07-12T04:19:21Z")

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littlerussian: this worked perfectly. You saved us. Thank you! Would love if this was an editor plugin.

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**Author:** ![anonymous\_user\_9cfab3bc](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_9cfab3bc](https://forums.unrealengine.com/u/anonymous_user_9cfab3bc)\
**Post date:** [July 12, 2017, 11:06pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/32 "2017-07-12T23:06:11Z")

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Hello, where do I put this code. Sorry Im just an archviz student not a coder.

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**Author:** ![anonymous\_user\_0df14252](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_0df14252](https://forums.unrealengine.com/u/anonymous_user_0df14252)\
**Post date:** [July 13, 2017, 2:01pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/33 "2017-07-13T14:01:27Z")

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link text  
This is the editor plugin. You need to compile it, because if I upload the binary I exceed the 5.2 MB

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**Author:** ![Jovimaca](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Jovimaca](https://forums.unrealengine.com/u/Jovimaca)\
**Post date:** [January 24, 2018, 8:14am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/34 "2018-01-24T08:14:21Z")

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That’s it! you saved our day 😃 thank you so much

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**Author:** ![laggyluk](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@laggyluk](https://forums.unrealengine.com/u/laggyluk)\
**Post date:** [May 11, 2019, 9:49am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/35 "2019-05-11T09:49:47Z")

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Made an editor plugin from that code above, cheers.

> **[GitHub - laggyluk/SwarmGuidFixer: UE4 Plugin fore resolving conflicting...](https://github.com/laggyluk/SwarmGuidFixer/)**
>
> UE4 Plugin fore resolving conflicting material IDs that cause errors in Swarm build - GitHub - laggyluk/SwarmGuidFixer: UE4 Plugin fore resolving conflicting material IDs that cause errors in Swarm...

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**Author:** ![kklimitkk](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@kklimitkk](https://forums.unrealengine.com/u/kklimitkk)\
**Post date:** [July 2, 2019, 4:57am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/36 "2019-07-02T04:57:50Z")

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thank you!!!

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**Author:** ![g1i7chp37s](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@g1i7chp37s](https://forums.unrealengine.com/u/g1i7chp37s)\
**Post date:** [July 17, 2019, 3:19pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/37 "2019-07-17T15:19:23Z")

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works ty!!!

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**Author:** ![di0deman](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@di0deman](https://forums.unrealengine.com/u/di0deman)\
**Post date:** [January 29, 2020, 9:04am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/38 "2020-01-29T09:04:01Z")

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Thank you for solving my problem.

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**Author:** ![ziotom2](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ziotom2](https://forums.unrealengine.com/u/ziotom2)\
**Post date:** [March 21, 2020, 4:12pm UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/39 "2020-03-21T16:12:53Z")

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it worked. thank you very much!!!

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**Author:** ![dimitri.jap](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@dimitri.jap](https://forums.unrealengine.com/u/dimitri.jap)\
**Post date:** [June 18, 2020, 1:51am UTC](https://forums.unrealengine.com/t/lighting-build-failed-swarm-failed-to-kick-off/287953/40 "2020-06-18T01:51:48Z")

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Bumping to say thanks to OP and the the users below for the solution/plugin.

Really wish they would implement a method to determine which material/mesh or object is being referenced to from the GUID. Just knowing what is causing the issue would have saved hours of frustration, instead of having to go through every single asset in your level.

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