# Swarm Failed to Kick Off. Rebuild Unreal Lightmass

**URL:** <https://forums.unrealengine.com/t/swarm-failed-to-kick-off-rebuild-unreal-lightmass/486272>\
**Category:** Rendering\
**Tags:** swarm-agent, unreal-engine, question\
**Created:** [July 16, 2021, 2:33am UTC](https://forums.unrealengine.com/t/swarm-failed-to-kick-off-rebuild-unreal-lightmass/486272 "2021-07-16T02:33:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![LNL227](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@LNL227](https://forums.unrealengine.com/u/LNL227)\
**Post date:** [July 16, 2021, 2:33am UTC](https://forums.unrealengine.com/t/swarm-failed-to-kick-off-rebuild-unreal-lightmass/486272/1 "2021-07-16T02:33:42Z")

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I can’t fix this problem even I clear the cache folder still didn’t work. I am currently using the launcher version of unreal engine and cannot find any solution because mostly are using the source build.