Intermittent C4D crash while rendering animation (local + Team Render) — call stack ends in LegionLib Scheduler — C4D 2025.3.3 / Corona 15

Corona Corona for Cinema 4D Corona for C4D :: Issues
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Versions

  • Chaos Corona: Version • 15 Build timestamp • May 25 2026 18:28:56

  • Cinema 4D: 2025.3.3

  • OS: Windows 11 Pro (build 26220)

  • GPU: NVIDIA RTX 5090, driver 610.47

What happens C4D crashes intermittently while rendering an animation. It happens both in local rendering and in Team Render (Team Render to Picture Viewer, animation, crash occurs on the master machine). At first it crashed after about 9 passes on a single frame. After I removed unused materials and recreated the render settings (they had been carried over from a pre-update Corona version), it now renders several full frames before crashing — but with the same call stack each time. The crash happens at the end of a frame / between frames.

Crashing thread (top frames — identical across ~5 separate crashes)

Corona_Release.dll:    Legion::Corona::DrMaster::numConnections + 0x3589a
Corona_Release.dll:    Legion::Corona::DrMaster::numConnections + 0x3c260
unknown:               0x00000254651CE2E4
unknown:               0x00000253D61CE2E4
Corona_Release.dll:    Legion::Corona::DrMaster::numConnections + 0x3c260
Corona_Release.dll:    Legion::Corona::DrMaster::numConnections + 0x434c3
LegionLib_Release.dll: Legion::Task::isRoot + 0xf8
LegionLib_Release.dll: Legion::Scheduler::popExecutionStack + 0x25b
LegionLib_Release.dll: Legion::Scheduler::~Scheduler + 0x78d
LegionLib_Release.dll: Legion::Thread::detach + 0xc8
LegionLib_Release.dll: Legion::yield + 0x19

Between the Corona frames there are two unresolved return addresses (shown as unknown), and the stack unwinds through Scheduler::~Scheduler and Thread::detach. I don’t know what that indicates — I’ll leave the interpretation to you. The C4D Critical_Log is empty on every crash.

Reproducibility Same call stack on ~5 separate crashes, in both local and Team Render. It’s intermittent — the render runs a different length each time before crashing. The machine runs 700+ threads during rendering.

Scene context The document has plugins from multiple render engines loaded (Corona + V-Ray + Redshift), plus ChaosScatter, Forester and Laubwerk. An earlier crash (before cleanup) also logged CRITICAL: Type constraint and type must not be set both [nodedescription_helper_impl.cpp(711)]; that message disappeared after I removed unused materials.

Already tried

  • Removed unused materials (this cleared the Type constraint critical message above)

  • Recreated the render settings after the Corona update

  • Denoiser off

  • Tested local vs Team Render — both crash with the same stack

Attachments Full C4D bug report (.txt) and thread dump attached. Minidump and the scene file available on request — happy to send the scene privately.

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Logs and minidump shared with devs as (CC4D-1380).

Continuing through support ticket #490350.