Unreal 4.17 crashes on startup on Linux

I cloned latest code from 4.17 branch, compiled and ran my project few times (each time without any changes). About 1 out of 4 times it crashed on startup, I think whenever I tried to push its window in background. Below is the call stack from Crashes folder which seem to come entirely from Unreal code. Also here’s whole crash folder

OS version Linux 4.10.0-27-generic (network name: shitalspitchlx)
Running 4 x86_64 processors (4 logical cores)
Exception was "SIGSEGV: invalid attempt to read memory at address 0x00000000000001f5"


Unknown!FLinuxPlatformStackWalk::CaptureStackBackTrace(unsigned long long*, unsigned int, void*) + some bytes
Unknown!FGenericPlatformStackWalk::StackWalkAndDump(char*, unsigned long, int, void*) + some bytes
Unknown!FLinuxCrashContext::CaptureStackTrace() + some bytes
Unknown!CommonLinuxCrashHandler(FGenericCrashContext const&) + some bytes
Unknown!PlatformCrashHandler(int, siginfo_t*, void*) + some bytes
Unknown!/lib/x86_64-linux-gnu/libpthread.so.0(+0x11390) [0x7fc373eb2390] + some bytes
Unknown!FLinuxApplication::FindWindowBySDLWindow(SDL_Window*) + some bytes
Unknown!FLinuxWindow::HitTest(SDL_Window*, SDL_Point const*, void*) + some bytes
Unknown!/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/libUE4Editor-Core.so(+0x7a9ad5) [0x7fc36d7aead5] + some bytes
Unknown!/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/libUE4Editor-Core.so(+0x7aa478) [0x7fc36d7af478] + some bytes
Unknown!/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/libUE4Editor-Core.so(+0x759063) [0x7fc36d75e063] + some bytes
Unknown!FLinuxPlatformMisc::PumpMessages(bool) + some bytes
/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/UE4Editor!FEngineLoop::Tick() + some bytes [Runtime/Core/Public/UObject/NameTypes.h:642]
/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/UE4Editor!GuardedMain(wchar_t const*) + some bytes [/home/shitals/GitHubSrc/UnrealEngine/Engine/Source/Runtime/Launch/Private/Launch.cpp:62]
Unknown!CommonLinuxMain(int, char**, int (*)(wchar_t const*)) + some bytes
Unknown!/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7fc3618cc830] + some bytes
Unknown!/home/shitals/GitHubSrc/UnrealEngine/Engine/Binaries/Linux/UE4Editor(_start+0x29) [0x416f79] + some bytes


Thanks for reporting. A few more details would be helpful in order to understand the issue.

  • What is your desktop environment?
  • Was the splash screen visible? If yes, was the mouse cursor inside it?
  • What exactly do you mean by “pushing the window into background”? Were you minimizing it or clicking on some other window to bring it into the focus?