4.5.1 crashes on startup (mac)

After updating to 4.5.1 on my 15" Early 2011 MBP, the Unreal Editor began crashing when launching. However previous versions of Unreal (4.4.3) worked perfectly fine. I receive this crash report when attempting to launch 4.5.1


Generating report for minidump

Application version 4.5.1-2336687+++depot+UE4-Releases+4.5
… built from changelist 2336687
… based on label ++depot+UE4-Releases+4.5

OS version
Running 4 x64 processors
Exception was “SIGSEGV: invalid attempt to access memory at address 0x3”

Source context from “”

FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, …) Address = 0x10cfe8380 (filename not found) [in UE4Editor-Core.dylib]
FPlatformOpenGLContext::Initialise(NSOpenGLContext*) Address = 0x121929710 (filename not found) [in UE4Editor-OpenGLDrv.dylib]
FPlatformOpenGLDevice::FPlatformOpenGLDevice() Address = 0x12194eb64 (filename not found) [in UE4Editor-OpenGLDrv.dylib]
FOpenGLDynamicRHI::FOpenGLDynamicRHI() Address = 0x12190b42c (filename not found) [in UE4Editor-OpenGLDrv.dylib]
FOpenGLDynamicRHIModule::CreateRHI() Address = 0x12193eb9e (filename not found) [in UE4Editor-OpenGLDrv.dylib]
RHIInit(bool) Address = 0x111a116d7 (filename not found) [in UE4Editor-RHI.dylib]
FEngineLoop::PreInit(wchar_t const*) Address = 0x10ce099ce (filename not found) [in UE4Editor]
GuardedMain(wchar_t const*) Address = 0x10ce1130f (filename not found) [in UE4Editor]
-[UE4AppDelegate() Address = 0x10ce195e5 (filename not found) [in UE4Editor]
-[FCocoaGameThread() Address = 0x10cf30574 (filename not found) [in UE4Editor-Core.dylib]
NSThread__main() Address = 0x7fff81c63b7a (filename not found) [in Foundation]
_pthread_body() Address = 0x7fff8ef512fc (filename not found) [in libsystem_pthread.dylib]
_pthread_body() Address = 0x7fff8ef51279 (filename not found) [in libsystem_pthread.dylib]
thread_start() Address = 0x7fff8ef4f4b1 (filename not found) [in libsystem_pthread.dylib]


I’ve tried uninstalling/reinstalling UE but ended up with no results.

Have no idea what else to do, any help is really appreciated!

OS X Yosemite (10.10),
2.2 GHz Core i7,
16 GB DDR3 1600MHz,
Radeon HD 6750m 1GB

Thank you for your report.

We will begin investigation into this issue as soon as possible. If we are unable to reproduce the problem, or need more information, we will follow up with some additional questions for you. Otherwise, we will post an ‘Answer’ once the issue has been logged in our bug database or we have a solution for it.

In the meantime, if possible, please also provide the UE4.log (Located: ~/Library/Logs/Unreal Engine/Editor/)
And the ProjectName.log (Located: ~/Library/Logs/Unreal Engine/ProjectNameEditor/)

Thank you.

I tested 4.5.1 on a very similar (the only difference in specs is the amount of memory) and I couldn’t reproduce this problem.

For some reason the engine cannot initialize OpenGL on your Mac, but I don’t have too many ideas on how could this happen, especially considering 4.4.3 used to work… Did you use 4.4.3 on Yosemite?

Maybe there’s a conflict with some other app running at the same time? Do you have anything else than Unreal Engine editor and Launcher running? Could you try without it?

Is this Mac, by any chance connected to an external display? Also, do you use gfxCardStatus app (https://gfx.io)? Could you install it? With this app you should be able to see which applications make the system switch to Radeon card, but also force use of either discreet or integrated graphics card.

Try is deleting the project preferences folder in ~/Library/Preferences/Unreal Engine/

If you’ve set an explicit display mask or renderer then that will be stored in the preferences & could conceivably cause this error.

Hi SirMars,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.


Apologies for the the late reply, 4.5.1 is now working. Turned out the issue involved the GPU switching within OS X. Downloading the gfxCardStatus app that suggested fixed the problem and everything runs great. Thank you for the helpful posts!