UE5.4 MacOS Building Lighting consistantly failing - connection timeout?

I’m using UE5.4 on a computer that belongs to a university - I am not able to change firewall settings to allow incoming connections.

I am also unable to successfully build lighting - at all. Even the simplest possible level with one dirctional light will fail - the ‘building’ popup shows 0% for a while and is followed by a lighting failed message.

Is the lighting issue related to the fact that I don’t have incoming connections available?

i’ve included below the relevent lines from the editor’s log, and a the UnrealLightmass log file from a recent crash.

This seems to be a common problem, but I have not seen anything like a solution anywhere.

thanks!

UE Log:
LogStaticLightingSystem: Warning: No importance volume found, so the scene bounding box was used. You can optimize your scene’s quality and lighting build times by adding importance volumes.
LogStaticLightingSystem: Running Lightmass w/ ImmediateImport mode ENABLED
LogStaticLightingSystem: Running Lightmass w/ ImmediateProcess mode ENABLED
LogStaticLightingSystem: Running Lightmass w/ Sorting mode ENABLED
LogStaticLightingSystem: Running Lightmass w/ Mapping paddings ENABLED
LogStaticLightingSystem: Running Lightmass w/ Mapping debug paddings DISABLED
LogEditorBuildUtils: Build time 0:00
LogUObjectHash: Compacting FUObjectHashTables data took 0.31ms
LogEOSSDK: LogEOS: Updating Product SDK Config, Time: 655.772034
LogEOSSDK: LogEOS: SDK Config Product Update Request Completed - No Change
LogEOSSDK: LogEOS: ScheduleNextSDKConfigDataUpdate - Time: 655.821960, Update Interval: 325.803711
LogStaticLightingSystem: Warning: Failed to build lighting!!! Lighting build failed.
DumpUnbuiltLightIteractions
Lights with unbuilt interactions: 1
Light DirectionalLight
Primitives with unbuilt interactions: 5
Primitive StaticMeshComponent /Game/barebones.barebones:PersistentLevel.StaticMeshActor_1.StaticMeshComponent0
Primitive StaticMeshComponent /Game/barebones.barebones:PersistentLevel.StaticMeshActor_2.StaticMeshComponent0
Primitive StaticMeshComponent /Game/barebones.barebones:PersistentLevel.StaticMeshActor_3.StaticMeshComponent0
Primitive StaticMeshComponent /Game/barebones.barebones:PersistentLevel.StaticMeshActor_4.StaticMeshComponent0
Primitive StaticMeshComponent /Game/barebones.barebones:PersistentLevel.StaticMeshActor_6.StaticMeshComponent0
Cmd: MAP CHECK NOTIFYRESULTS
MapCheck: Error: WorldSettings Maps need lighting rebuilt
MapCheck: Map check complete: 1 Error(s), 0 Warning(s), took 2.288ms to complete.

UnrealLightmass log:
ÿþStats thread started at 0.116802

ICU TimeZone Detection - Raw Offset: -5:00, Platform Override: ‘’

Session CrashGUID >====================================================
Session CrashGUID > UECC-Mac-C834F112D84FDAEA9DD8EFAE60FC25BD
Session CrashGUID >====================================================

No local boot hotfix file found at: [/Users/wsack/Library/Application Support/Epic/UnrealLightmass/Saved/PersistentDownloadDir/HotfixForNextBoot.txt]

Mounting Engine plugin UdpMessaging

ExecutableName: UnrealLightmass

Build: ++UE5+Release-5.4-CL-35576357

Platform=MacEditor

MachineId=c1d15ad40943b78c676f538c73bb1943

DeviceId=

Engine Version: 5.4.4-35576357+++UE5+Release-5.4

Compatible Engine Version: 5.4.0-33043543+++UE5+Release-5.4

Net CL: 33043543

OS: macOS 14.7.3 (23H417), CPU: Apple M2 Pro, GPU: Apple M2 Pro

Compiled (64-bit): Aug 16 2024 00:53:22

Architecture: x64

Compiled with Clang: 14.0.0 (clang-1400.0.29.202)

Build Configuration: Development

Branch Name: ++UE5+Release-5.4

Command Line: D3DE94C9AB4B5F80BABA41A2A8BAE128 -installed -Messaging -nostdout

Base Directory: /Users/wsack/UE_5.4/Engine/Binaries/Mac/

Allocator: ANSI

Installed Engine Build: 1

This binary is optimized with LTO: no, PGO: no, instrumented for PGO data collection: no

Number of dev versions registered: 36

Dev-Blueprints (B0D832E4-1F89-4F0D-ACCF-7EB736FD4AA2): 10

Dev-Build (E1C64328-A22C-4D53-A36C-8E866417BD8C): 0

Dev-Core (375EC13C-06E4-48FB-B500-84F0262A717E): 4

Dev-Editor (E4B068ED-F494-42E9-A231-DA0B2E46BB41): 40

Dev-Framework (CFFC743F-43B0-4480-9391-14DF171D2073): 37

Dev-Mobile (B02B49B5-BB20-44E9-A304-32B752E40360): 3

Dev-Networking (A4E4105C-59A1-49B5-A7C5-40C4547EDFEE): 0

Dev-Online (39C831C9-5AE6-47DC-9A44-9C173E1C8E7C): 0

Dev-Physics (78F01B33-EBEA-4F98-B9B4-84EACCB95AA2): 20

Dev-Platform (6631380F-2D4D-43E0-8009-CF276956A95A): 0

Dev-Rendering (12F88B9F-8875-4AFC-A67C-D90C383ABD29): 48

Dev-Sequencer (7B5AE74C-D270-4C10-A958-57980B212A5A): 13

Dev-VR (D7296918-1DD6-4BDD-9DE2-64A83CC13884): 3

Dev-LoadTimes (C2A15278-BFE7-4AFE-6C17-90FF531DF755): 1

Private-Geometry (6EACA3D4-40EC-4CC1-B786-8BED09428FC5): 3

Dev-AnimPhys (29E575DD-E0A3-4627-9D10-D276232CDCEA): 17

Dev-Anim (AF43A65D-7FD3-4947-9873-3E8ED9C1BB05): 15

Dev-ReflectionCapture (6B266CEC-1EC7-4B8F-A30B-E4D90942FC07): 1

Dev-Automation (0DF73D61-A23F-47EA-B727-89E90C41499A): 1

FortniteMain (601D1886-AC64-4F84-AA16-D3DE0DEAC7D6): 134

FortniteValkyrie (8DBC2C5B-54A7-43E0-A768-FCBB7DA29060): 8

FortniteSeason (5B4C06B7-2463-4AF8-805B-BF70CDF5D0DD): 12

FortniteRelease (E7086368-6B23-4C58-8439-1B7016265E91): 13

Dev-Enterprise (9DFFBCD6-494F-0158-E221-12823C92A888): 10

Dev-Niagara (F2AED0AC-9AFE-416F-8664-AA7FFA26D6FC): 1

Dev-Destruction (174F1F0B-B4C6-45A5-B13F-2EE8D0FB917D): 10

Dev-Physics-Ext (35F94A83-E258-406C-A318-09F59610247C): 41

Dev-PhysicsMaterial-Chaos (B68FC16E-8B1B-42E2-B453-215C058844FE): 1

Dev-CineCamera (B2E18506-4273-CFC2-A54E-F4BB758BBA07): 1

Dev-VirtualProduction (64F58936-FD1B-42BA-BA96-7289D5D0FA4E): 1

UE5-Main (697DD581-E64F-41AB-AA4A-51ECBEB7B628): 119

UE5-Release (D89B5E42-24BD-4D46-8412-ACA8DF641779): 51

UE5-PrivateFrosty (59DA5D52-1232-4948-B878-597870B8E98B): 8

UE5-Dev-Cooker (26075A32-730F-4708-88E9-8C32F1599D05): 0

Dev-MediaFramework (6F0ED827-A609-4895-9C91-998D90180EA4): 2

UE5-Dev-LWCRendering (30D58BE3-95EA-4282-A6E3-B159D8EBB06A): 1

Presizing for max 100000 objects, including 0 objects not considered by GC, pre-allocating 0 bytes for permanent pool.

Object subsystem initialized

Applying CVar settings from Section [Startup] File […/…/…/Engine/Config/ConsoleVariables.ini]

CVar [[r.DumpShaderDebugInfo:2]] deferred - dummy variable created

CVar [[r.Shaders.WarningsAsErrors:0 ;; 0: off, 1: global shaders, 2: all]] deferred - dummy variable created

CVar [[p.chaos.AllowCreatePhysxBodies:1]] deferred - dummy variable created

CVar [[fx.SkipVectorVMBackendOptimizations:1]] deferred - dummy variable created

Applying CVar settings from Section [Startup_Mac] File […/…/…/Engine/Config/ConsoleVariables.ini]

Applying CVar settings from Section [ConsoleVariables] File [Engine]

CVar [[r.HairStrands.Visibility.MSAA.SamplePerPixel:1]] deferred - dummy variable created

CVar [[r.SceneCulling.ExplicitCellBounds:1]] deferred - dummy variable created

Set CVar [[memory.MemoryPressureCriticalThresholdMB:512]]

macOS 14.7.3 (23H417)

Model: Mac14,9

CPU: Apple M2 Pro

CPU Page size=4096, Cores=10, HT=10

Computer: cast-wsackml

User: wsack

High frequency timer resolution =1000.000000 MHz

Power Source: AC Power

Memory total: Physical=16.0GB (16GB approx) Pagefile=0.0GB Virtual=16.0GB

306 objects as part of root set at end of initial load.

52992 out of 0 bytes used by permanent object pool.

CloseDisregardForGC: 0/0 objects in disregard for GC pool

Using OS detected language (en-US).

Using OS detected locale (en-US).

No specific localization for ‘en-US’ exists, so ‘en’ will be used for the language.

Using OS detected language (en-US).

Using OS detected locale (en-US).

No localization for ‘en-US’ exists, so ‘en’ will be used for the language.

No localization for ‘en-US’ exists, so ‘en’ will be used for the locale.

Processed 2 localized package path(s) for 1 prioritized culture(s) in 0.000103 seconds

Initializing bridge on interface 0.0.0.0:0 to multicast group 230.0.0.1:6666.

Unicast socket bound to ‘0.0.0.0:56183’.

Added local interface ‘10.83.11.225’ to multicast group ‘230.0.0.1:6666’

Added local interface ‘128.205.121.143’ to multicast group ‘230.0.0.1:6666’

Lightmass Mac started on: cast-wsackml. Command-line: D3DE94C9AB4B5F80BABA41A2A8BAE128 -installed -Messaging -nostdout

Processing scene GUID: D3DE94C9AB4B5F80BABA41A2A8BAE128 with 10 threads

Building static lighting…

Timed out waiting for the recipient (TimeWaitingSec = 60.452936)

Measured CPU frequency: 1.00 GHz

FStaticLightingSystem started using GKDOPMaxTrisPerLeaf: 4

Number of texture mappings: 5

Number of fluid mappings: 0

Number of landscape mappings: 0

Number of BSP mappings: 0

Number of static mesh instance mappings: 5

Scene surface area calculated at 1.439 million units (34.466% of the estimated 4.175 million units)

Importance volume surface area calculated at 1.439 million units (0.000% of the estimated 0.000 million units)

Embree Build 0.0s

Collision Mesh Overview:

Num Triangles : 816

MeshInfos : 0.0Mb

UVs : 0.0Mb

LightmapUVs : 0.0Mb

Embree Used Memory : 0.1Mb

Processing…

Timed out waiting for the recipient (TimeWaitingSec = 60.435317)

Same here. Migrated project from 5.3.2 to 5.5.3 and now I can’t build lighting on any level. It’s stuck on 0% and fails with “MapCheck: Error: WorldSettings Maps need lighting rebuilt”. Even for a new empty level.

Did you manage to solve it?

here is what i’ve kind of figured out: the lighting is built by a separate process running on the same host machine - the editor needs to communicate with that process over a socket, and needs a particular port or ports open to do that. The ports are blocked by default unless they’re enabled by changing the mac firewall settings.

in my particular case, i’m hoping to convince the university’s IT staff to allow an exception for the ports we need.

for anyone else, check all the logs you can to see if it’s a matter of the editor timing out waiting for a connection to the Lightmass process - maybe your firewall was reset or maybe the rrequired ports have changed?

still in the dark (pun intentional)

Yeah, I found this post that seems to confirm that:

UDP was already enabled for me and I manually added the UnrealEditor/Lightmass to the MacOS firewall (they were already added for the other version).

Unfortunately it didn’t help. Also tried a couple of other things like disabling nanite, lumen, virtual shadow maps and also deleting everything under Saved and DerivedDataCache for full rebuild but still no luck.

Tried disabling the firewall completely and that solved it. Not a long-term solution though. All Unreal processes that are active in the activity monitor are already allowed in the firewall settings so I have no idea why it’s not working.