# Unreal (5.4.4 and 5.6 Preview) Lightmass on Mac stopping at 0%

**URL:** <https://forums.unrealengine.com/t/unreal-5-4-4-and-5-6-preview-lightmass-on-mac-stopping-at-0/2530543>\
**Category:** Rendering\
**Tags:** apple, Lightmass, building-lighting, baked-lighting, Macos, unreal-engine, question\
**Created:** [May 27, 2025, 7:08pm UTC](https://forums.unrealengine.com/t/unreal-5-4-4-and-5-6-preview-lightmass-on-mac-stopping-at-0/2530543 "2025-05-27T19:08:22Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![TommyBoy](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@TommyBoy](https://forums.unrealengine.com/u/TommyBoy)\
**Post date:** [August 1, 2025, 7:01pm UTC](https://forums.unrealengine.com/t/unreal-5-4-4-and-5-6-preview-lightmass-on-mac-stopping-at-0/2530543/7 "2025-08-01T19:01:44Z")

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That is a swarm issue… just download the file here and follow the instructions on where to put it in the engine… [UE 5.6 has no swarm manager - #5 by Arkiras](https://forums.unrealengine.com/t/ue-5-6-has-no-swarm-manager/2539483/5) The guy provides a file called dotnet.zip

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