Hot reload - Crash

In 4.5.1:

When HotReloading in DevelopmentEditor Configuration, the Editor shutdown after the build without any crash reports.
I open the editor with VS studio and launch in debug and here are the logs that I have:

This is the end of the HotReload log before the “crash”.

[2014.11.11-20.25.06:491][771]LogClass: ZoomTickFunction HotReload.
[2014.11.11-20.25.06:492][771]LogClass: TimedMaterialParameter HotReload.
First- exception at 0x000007FEE0172BE4 (UE4Editor-CoreUObject.dll) in UE4Editor.exe: 0xC00000FD: Stack overflow (parameters: 0x0000000000000001, 0x0000000000203FE8).
Unhandled exception at 0x000007FEE0172BE4 (UE4Editor-CoreUObject.dll) in UE4Editor.exe: 0xC00000FD: Stack overflow (parameters: 0x0000000000000001, 0x0000000000203FE8).

So I have a bug while loading the “structs”.

I don’t know if it fails on the last log struct, but in case, here is the code:

/** used to animate a material parameter over time from any Actor */
struct FTimedMaterialParameter

	/** the material to set parameters on */
	TWeakObjectPtr<class UMaterialInstanceDynamic> MI;
	/** parameter name */
	FName ParamName;
	/** the curve to retrieve values from */
	UCurveBase* ParamCurve;
	/** elapsed time along the curve */
	float ElapsedTime;
	/** whether to clear the parameter when the curve completes */
	bool bClearOnComplete;

		: MI(NULL)
	FTimedMaterialParameter(UMaterialInstanceDynamic* InMI, FName InParamName, UCurveBase* InCurve, bool bInClearOnComplete = true)
		: MI(InMI), ParamName(InParamName), ParamCurve(InCurve), ElapsedTime(0.0f), bClearOnComplete(bInClearOnComplete)


Do you need additional information?

If you need a full game code to test, you can take UE4 code as Hot Reload is not working.


Hi ,

I tried to reproduce this using both the binary version of the Editor, as well as one built from source code, and I was not able to create a crash. Are you able to reproduce this crash in a new project, or does it only occur in your project?


I didn’t had the time yet to test the new project. For the moment, it occurs on my project, but also in UnrealTournament code. Have you been able to hotreload UT code, because I asked on UT forums and it seems that no one is able to get it working.

Do you know when the logger write “LogClass: TimedMaterialParameter HotReload.” if it starts the reload of this struct or if the struc passed and the process moved to the next one? Just to try to find what cause the crash.


I pulled down the UT code that was current as of about 4 hours ago. I did see a crash when initiating a hot recompile, but it did not seem to be related to any structs. However, that crash then prevented me from being able to open UT again. I don’t think it is the same crash that you are seeing.

Could you provide the callstack for the crash you are seeing?

Hey -

We’re still investigating the crash, however I would like to ask if you’re still having this issue on the latest version of the engine? If this is still occurring for you could you post a copy of the callstack as well as the log files from the crash?


Seems to be fine now in 4.6. I will reopen the thread if needed, but you can mark it as solved now.