I've seen this error before on Windows Store (Phone & Windows RT,) but it generally wasn't a fatal error. It was sufficient usually to switch to Master release mode and ignore the error. It's not present on any other platforms. With the latest app I'm porting in Unity, I now consistently receive this error message in the console prior to a hard crash on Windows Phone. It's generally preceded by an unused memory cleanup: Code (csharp): Unloading 43 unused Assets to reduce memory usage. Loaded Objects now: 10718. Operation took 968.524536 ms. System memory in use: 39.0 MB. index < m_size (Filename: C:\buildslave\unity\build\Runtime/Utilities/dynamic_array.h Line: 303) I can't find any documentation on where this log message comes from, I'd be grateful to know where in the Unity code this message can be produced as I have no idea where to start looking nor can I seem to catch this with a breakpoint.