The same callstack appears in 4.24.3 (CL-11590370) but only when playing a Sequence with a Media Track that has a ImgMediaSource and Media Texture set on it. These repro steps work for 4.25 and 4.26 since the crash is triggered earlier.
This was tested in 4.25.1 (CL-13594126) and reproduced in Main 4.26 (CL-13653677)
Results: The Editor crashes
Expected: The Editor doesn't crash
[2020.06.18-18.22.32:206][634]LogThreadingWindows: Error: Runnable thread PoolThread 23 crashed. [2020.06.18-18.22.32:206][634]LogWindows: Error: === Critical error: === [2020.06.18-18.22.32:206][634]LogWindows: Error: [2020.06.18-18.22.32:206][634]LogWindows: Error: Fatal error! [2020.06.18-18.22.32:206][634]LogWindows: Error: [2020.06.18-18.22.32:206][634]LogWindows: Error: Unhandled Exception: 0xe06d7363 [2020.06.18-18.22.32:206][634]LogWindows: Error: [2020.06.18-18.22.32:206][634]LogWindows: Error: [Callstack] 0x00007ffd1dcea799 KERNELBASE.dll!UnknownFunction [] [2020.06.18-18.22.32:206][634]LogWindows: Error: [Callstack] 0x00007ffd076443f1 VCRUNTIME140.dll!UnknownFunction [] [2020.06.18-18.22.32:206][634]LogWindows: Error: [Callstack] 0x00007ffd20d40616 ntdll.dll!UnknownFunction [] [2020.06.18-18.22.32:206][634]LogWindows: Error: [2020.06.18-18.22.32:206][634]LogWindows: Error: Crash in runnable thread PoolThread 23 Unhandled Exception: 0xe06d7363 KERNELBASE VCRUNTIME140 ntdll UE4Editor_OpenExrWrapper!Imf_2_3::InputFile::InputFile() UE4Editor_OpenExrWrapper!Imf_2_3::RgbaInputFile::RgbaInputFile() UE4Editor_OpenExrWrapper!FRgbaInputFile::FRgbaInputFile() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\Media\ImgMedia\Source\OpenExrWrapper\Private\OpenExrWrapper.cpp:39] UE4Editor_ImgMedia!FExrImgMediaReader::GetFrameInfo() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\Media\ImgMedia\Source\ImgMedia\Private\Readers\ExrImgMediaReader.cpp:32] UE4Editor_ImgMedia!FImgMediaLoader::LoadSequence() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\Media\ImgMedia\Source\ImgMedia\Private\Loader\ImgMediaLoader.cpp:312] UE4Editor_ImgMedia!<lambda_0a5c41913f27216a2c285dd123e81207>::operator()() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\Media\ImgMedia\Source\ImgMedia\Private\Player\ImgMediaPlayer.cpp:203] UE4Editor_ImgMedia!SetPromise<TUniqueFunction<void __cdecl(void)> &>() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Async\Async.h:57] UE4Editor_ImgMedia!TAsyncQueuedWork<void>::DoThreadedWork() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Async\Async.h:224] UE4Editor_Core!FQueuedThread::Run() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\HAL\ThreadingBase.cpp:855] UE4Editor_Core!FRunnableThreadWin::Run() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsRunnableThread.cpp:86]
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