1.8.0.10, built 2026-07-31 15:18:14 UTC

Engine version 191843

The clean repro needs one mod, and any mod reproduces it:

• WhereAmI - 5965550F24A0C152

I chose that one because it adds no assets and no weather code. I first saw the error with my own mod:

• Dynamic Weather Mod - 6A0EE1A1D5261244

Both give the same count on the same scenario. I also see it with a 38 to 41 mod list, where the count reaches 403,270 lines in one session. The error does not appear in the sessions with no mods.

WHAT HAPPENS

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When an addon is loaded, material finalization cannot open the six default thermal profiles that the engine has hardcoded. Each affected material slot writes three log lines. One load of Capture & Hold - Castle writes about 78,400 error lines and makes error.log 23 MB. The resource is present, so this is an open failure and not missing content:

- The exe holds the GUID and the path:

{CC547D988287BF7C}system/thermal/thermalProfileDefault.conf

- addons/core/resourceDatabase.rdb holds the same GUID and path.

- addons/core/data.pak holds thermalProfileDefault.conf and its five

siblings.

Script has no thermal profile API, so no mod can cause this from script. The failure is inside the engine.

STEPS TO REPRODUCE

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1. Start the game with no mods.

2. Host the scenario Capture & Hold - Castle.

Mission {F1A1BEA67132113E}Missions/CAH_Castle.conf

3. Go back to the main menu.

4. Enable exactly one mod. I used WhereAmI (5965550F24A0C152).

5. Host the same scenario again.

6. Open the newest folder in Documents/My Games/ArmaReforger/logs and search

console.log for "thermal profile".

ACTUAL RESULT

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The modded session writes this triplet once for each affected material slot:

MATERIAL : Finalizing material @"{E9C191F08ACE8804}Assets/Rocks/Granite/Data/GraniteStone_01.emat"

RESOURCES : GetResourceObject @"{CC547D988287BF7C}system/thermal/thermalProfileDefault.conf"

RESOURCES (E): Failed to open

RESOURCES (E): 'system/thermal/thermalProfileDefault.conf' is not a valid thermal profile!

Counts from one Capture & Hold - Castle load with WhereAmI, log folder

logs_2026-08-21_18-09-06:

77,607 system/thermal/thermalProfileDefault.conf

498 system/thermal/thermalProfileTreeCrownDefault.conf

154 system/thermal/thermalProfileTreeTrunkDefault.conf

78 system/thermal/thermalProfileTerrainDefault.conf

24 system/thermal/thermalProfileGrassDefault.conf

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78,361 total, in console.log and again in error.log

Nothing else in the session fails to open. Every "Failed to open" in the whole log is one of these system/thermal files. The lines occur during world load, and again when a new asset streams in. The last group in one run came from a bee prefab that spawned one minute after the load:

ENTITY : Create entity @"ENTITY:6917529027641082347" ('GenericEntity')

ENTITY : EntityPrefabUse @"{B6B4DD03DE9C0B3F}Prefabs/Animals/Apis/Apis_One.et"

RESOURCES : MeshObjectLoad @"{D6A3596FEAD7E9C0}Assets/Animals/Apis/Apis.xob"

MATERIAL : Finalizing material @"{63890962B5851224}Assets/Animals/Apis/Data/Apis.emat"

RESOURCES : GetResourceObject @"{CC547D988287BF7C}system/thermal/thermalProfileDefault.conf"

RESOURCES (E): Failed to open

EXPECTED RESULT

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The engine opens the default thermal profile that it shipped and that its own resource database registers. No error line.

WHAT I MEASURED

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One process, one machine, one scenario, three sessions in sequence, log folder logs_2026-08-21_17-59-30:

Session 1 no mods, CAH_Castle 0 lines

Session 2 one mod, CAH_Castle 78,814 lines

Session 3 no mods, CAH_Castle 0 lines

The mod set is the only difference between the sessions. One point of caution that you can settle faster than I can: the sessions with no mods write no resource logging at all - 0 "Material load" lines and 0 "MeshObjectLoad" lines, against 4,567 and 1,511 in the modded session. So an addon may only make an existing failure visible, instead of causing it. Please run a session with no mods at -logLevel verbose and compare. Either answer

still leaves the open failure to fix.

POSSIBLE CAUSE

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The resource database index moves when an addon is present:

No mods: id=0 ArmaReforger, id=1 core, id=2 profile, id=3 logs

One mod: id=0 <the mod>, id=1 ArmaReforger, id=2 core, id=3 profile,

id=4 logs

Only resources that belong to core fail, and only the ones the engine resolves from its own hardcoded GUID list. The GUID resolves correctly - the engine prints the right path - but the file open fails. An index that was captured before the mount order changed would explain both facts. This is my inference from the logs, not a proof.

IMPACT

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1. Mainly log noise. 78,000 to 400,000 error lines for each world load. error.log reaches 23 MB and holds almost nothing else, so it stops being sable for server admins and for mod authors who look for their own errors. Dedicated servers write this on every restart.

2. Thermal fidelity, if the fallback really does not load. Every material that leaves TIThermalProfile empty then has no thermal profile in a modded session. That affects what thermal optics show for stock assets such as rocks, terrain, grass, tree crowns and tree trunks.