Crash accessing Body Setup during cook

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1

Hi,

we are experiencing random crashes during cook. After finding this question [Content removed]

we’ve integrated this commit:

https://github.com/EpicGames/UnrealEngine/commit/869644589dfec1f758b8340244156c03da923b51

However the crashes are still occurring.

We’ve somewhat recently introduced custom collision meshes for many of our meshes, though we cannot be certain whether that is the issue.

All the custom collisions are set via “UGeometryScriptLibrary_CollisionFunctions::SetStaticMeshCustomComplexCollision” and the meshes use ComplexCollisionAsSimple.

Any help would be appreciated.

Regards,

Max

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2

Hi [mention removed],

I have just been assigned this case. Thank you for reporting the crash. Since you mentioned that these crashes occur randomly, would it be possible for you to share the crash call stack so we have a bit more context about what is happening?

I will also investigate whether there have been any fixes for engine crashes in the most recent versions. I will update the thread shortly.

Regards,

Joan

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3

Hi,

unfortunately we had another cookworker crash with an almost identical stack trace today.

Any chance there are more options to fix the issue?

Regards,

Max

New stack just in case:

UnrealEditor-Engine.dll!FFormatContainer::Contains() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\CoreUObject\Public\Serialization\BulkData.h:1149]

UnrealEditor-Engine.dll!UBodySetup::TryGetCookedData() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodySetup.cpp:1467]

UnrealEditor-Engine.dll!UBodySetup::IsCachedCookedPlatformDataLoaded() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodySetup.cpp:1225]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::RouteIsCachedCookedPlatformDataLoaded() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:12667]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::CallBeginCacheOnObjects() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4377]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::BeginCacheObjectsToMove() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3787]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveGenerationPackage() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3637]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveGenerationPackage() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3660]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveInternal() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4256]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSave() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4039]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PumpRuntimeSaves() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:5031]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickMainCookLoop() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1528]

UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickCookWorker() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1504]

UnrealEditor-UnrealEd.dll!UCookCommandlet::CookAsCookWorker() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:645]

UnrealEditor-UnrealEd.dll!UCookCommandlet::Main() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:263]

UnrealEditor-Cmd.exe!FEngineLoop::PreInitPostStartupScreen() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:3860]

UnrealEditor-Cmd.exe!GuardedMain() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Launch.cpp:143]

UnrealEditor-Cmd.exe!GuardedMainWrapper() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:128]

UnrealEditor-Cmd.exe!LaunchWindowsStartup() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:282]

UnrealEditor-Cmd.exe!WinMain() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:339]

UnrealEditor-Cmd.exe!__scrt_common_main_seh() [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]

KERNEL32.DLL!UnknownFunction []

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4

Hi folks.

This is something we have been chasing for a while now on the epic side. I’ve just pinged the dev who submitted the fix in order to find out what the status is and I’ll revert here when I know more!

Best

Geoff Stacey

Developer Relations

EPIC Games

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5

Hi Max,

Yes the fix was reverted because of deadlocks. The latest is that Matt has a fix, but it is blocked pending submission of another bug, we don’t have an ETA but I’ve asked for an update as soon as we know more.

Best

Geoff

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6

Hi Max,

Yes, I’d suggest integrating that CL (51786083). You may need to take another CL though, but try without first. The other one is 51598166.

Let me know if this fixes the issues!

Best

Geoff

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7

I did add the callstack in the call stack section of the Initial post but I guess thats not visible?

here it is again:

2026.02.16-01.45.55:372][ 0]LogWindows: Error: begin: stack for UAT

[2026.02.16-01.45.55:373][ 0]LogWindows: Error: === Critical error: ===

[2026.02.16-01.45.55:373][ 0]LogWindows: Error:

[2026.02.16-01.45.55:373][ 0]LogWindows: Error: Fatal error!

[2026.02.16-01.45.55:373][ 0]LogWindows: Error:

[2026.02.16-01.45.55:373][ 0]LogWindows: Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000000

[2026.02.16-01.45.55:373][ 0]LogWindows: Error:

[2026.02.16-01.45.55:373][ 0]LogWindows: Error: [Callstack] 0x00007ffa57293809 UnrealEditor-Engine.dll!FFormatContainer::Contains() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\CoreUObject\Public\Serialization\BulkData.h:1149]

[2026.02.16-01.45.55:373][ 0]LogWindows: Error: [Callstack] 0x00007ffa572f6a53 UnrealEditor-Engine.dll!UBodySetup::TryGetCookedData() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodySetup.cpp:1445]

[2026.02.16-01.45.55:374][ 0]LogWindows: Error: [Callstack] 0x00007ffa572c2c99 UnrealEditor-Engine.dll!UBodySetup::IsCachedCookedPlatformDataLoaded() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Engine\Private\PhysicsEngine\BodySetup.cpp:1223]

[2026.02.16-01.45.55:374][ 0]LogWindows: Error: [Callstack] 0x00007ffa546d592c UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::RouteIsCachedCookedPlatformDataLoaded() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:12667]

[2026.02.16-01.45.55:374][ 0]LogWindows: Error: [Callstack] 0x00007ffa54698ef9 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::CallBeginCacheOnObjects() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4377]

[2026.02.16-01.45.55:374][ 0]LogWindows: Error: [Callstack] 0x00007ffa54694978 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::BeginCacheObjectsToMove() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3787]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546ca30f UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveGenerationPackage() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3637]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546ca3ba UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveGenerationPackage() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:3660]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546cab78 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSaveInternal() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4256]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546c9f9d UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PrepareSave() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:4039]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546cecf4 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PumpRuntimeSaves() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:5031]

[2026.02.16-01.45.55:375][ 0]LogWindows: Error: [Callstack] 0x00007ffa546de1f4 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickMainCookLoop() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1528]

[2026.02.16-01.45.55:376][ 0]LogWindows: Error: [Callstack] 0x00007ffa546dd97c UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickCookByTheBook() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1408]

[2026.02.16-01.45.55:376][ 0]LogWindows: Error: [Callstack] 0x00007ffa53342d20 UnrealEditor-UnrealEd.dll!UCookCommandlet::RunCookByTheBookCook() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:598]

[2026.02.16-01.45.55:376][ 0]LogWindows: Error: [Callstack] 0x00007ffa533036ca UnrealEditor-UnrealEd.dll!UCookCommandlet::CookByTheBook() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:550]

[2026.02.16-01.45.55:376][ 0]LogWindows: Error: [Callstack] 0x00007ffa5331fe83 UnrealEditor-UnrealEd.dll!UCookCommandlet::Main() [C:\Development\UnrealEngine\5.6\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:269]

[2026.02.16-01.45.55:376][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0ac8fa0 UnrealEditor-Cmd.exe!FEngineLoop::PreInitPostStartupScreen() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:3860]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0abe39c UnrealEditor-Cmd.exe!GuardedMain() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Launch.cpp:143]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0abe6ba UnrealEditor-Cmd.exe!GuardedMainWrapper() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:128]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0ac209e UnrealEditor-Cmd.exe!LaunchWindowsStartup() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:282]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0ad4e44 UnrealEditor-Cmd.exe!WinMain() [C:\Development\UnrealEngine\5.6\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:339]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ff7c0ad7466 UnrealEditor-Cmd.exe!__scrt_common_main_seh() [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]

[2026.02.16-01.45.55:377][ 0]LogWindows: Error: [Callstack] 0x00007ffb209ce8d7 KERNEL32.DLL!UnknownFunction []

[2026.02.16-01.45.55:377][ 0]LogWindows: Error:

[2026.02.16-01.45.55:378][ 0]LogWindows: Error: end: stack for UAT

Regards,

Max

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8

Hi Max,

Thanks for the callstack. Would it be possible to test the following commit and sees if it fixes your issue?

https://github.com/EpicGames/UnrealEngine/commit/44ff59af31a83799965f2f3fe74ae4e247aff2d9

This change changes how collision data is handled during cooking. Previously, the engine could end up referencing collision data that was no longer valid, which could lead to crashes. Will keep trying to get a consistent reproduction project.

Best Regards,

Joan

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9

Hi,

I’ve integrated the fix. Will monitor if the crash continues to appear over the next few builds.

Regards,

Max

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10

Hi Max!

Will take again a look today and see if there has been any updating regarding this issue from the epic devs.

Best Regards,

Joan

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11

Any Updates?

I do see a commit on github but it seems to have been reverted this week for some reason.

Regards,

Max

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12

Hi [mention removed]​,

Sorry for the delay. I’ve had several issues with my working setup and have been quite limited. I’m now fully back and will check this today. If this case turns out to be a bit tricky, I’ll forward it directly to Epic so an Unreal developer can take a closer look at it.

We will need a solid repro project so Epic can properly debug the issue and work on a fix, or at least so I can verify whether this has already been addressed in the development version of the engine. I’ll focus today on creating this repro project based on the hints you provided and see if that helps an Epic developer investigate it.

If you’ve found any additional hints or have a repro project you can share with us, please let me know.

Best regards,

Joan

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13

Hi,

since this is a race condition I highly doubt it is easy to create a reliable reproduction case.

However since @mattpeters is clearly already working on the issue I doubt they are unaware of it. My main question is just why the commit was reverted. It seems to be working fine for us.

https://github.com/EpicGames/UnrealEngine/commits/ue5\-main/Engine/Source/Runtime/Engine/Private/PhysicsEngine/BodySetup.cpp

Regards,

Max

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14

Hi,

any updates on this?

We’ve since got some reports of freezes during cook which might be related to the commit and why it was reverted.

We are considering changing the customized collision to an LOD and setting the collision to use that LOD. Though we’re uncertain if that would actually help.

Regards,

Max

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15

Hi Geoff,

I see a new commit was added, any updates? Was wondering if it makes sense to integrate that. We’ve only encountered the deadlock a couple times, but its quite annoying when we do.

Regards,

Max

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