Event dispatcher causes engine to crash


I have been using unreal engine in a class and have been experiencing a issue that I can not solve, nor can my professor. When ever I use a event dispatcher in a project they engine crashes upon saving/compiling. It will save/compile the first time however all subsequent attempts result in the engine crashing, also it will crash when I try to run it.

Iv heard that others have experienced these issues before, and almost everyone in my class is having the same problem.
Does anyone know of a fix for this problem?
And if not is there something else I could use instead of a event dispatcher that would perform the same task?

Thank you

There is an event dispatcher sample in the content examples (Blueprint Communications level). Have you tried to run the content example to see if it crashes UE4?

I just ran it today on 4.7.0 and had no problems (and it’s worked on 4.6.1 for me)

If the content example event dispatcher works on your machines without crashing, it may be an implementation error or a problem in the project. But, before we make that assessment and travel down that road, we’d have to rule out a few possibilities :slight_smile:

hey there,

can you show us where you set up the dispatchers?

btw. Interfaces can be an alternative to use

edit: does the log-/dmpfile give you any hints? Find them in /Game/Saved/Logs


I have tried several of the content examples and as with any custom project i create (that includes dispatcher) it will run successfully until i close the project and then reopen it again on a latter date. Also i have found if i unchecked “auto recompile blueprints” under play in editor preferences, I can then play the project but it will still crash the moment i attempt to change the project and re-save (including if i try to remove a even dispatcher from a project).

I have considered that maybe I am just doing something wrong, so il try to explain what i do. First i create a event dispatcher in a class blueprint from the event dispatch button on the left of the blueprint editor. Then I make sure the object is still selected in the editor and open the level blueprint. I right click in an empty area of the blueprint editor and type in the name of the event dispatcher i just created, and add it into the level blueprint. So far everyone I know that has been using event dispatchers in my class has experienced similar issues, even though we are all using our own computers not common lab computers.

The following is the error i receive when the engine crashes and closes


Unknown exception - code 00000001 (first/second chance not available)

Assertion failed: TargetDelegate [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.6\Engine\Source\Editor\UnrealEd\Private\Kismet2\BlueprintEditorUtils.cpp] [Line: 5407] 

KERNELBASE + 35740 bytes
UE4Editor_Core + 3092349 bytes
UE4Editor_Core + 1597688 bytes
UE4Editor_Core + 1479058 bytes
UE4Editor_UnrealEd + 9502651 bytes
UE4Editor_Engine + 5012673 bytes
UE4Editor_UnrealEd + 9881575 bytes
UE4Editor_UnrealEd + 4557402 bytes
UE4Editor_UnrealEd + 4660963 bytes
UE4Editor_UnrealEd + 1801811 bytes
UE4Editor_UnrealEd + 6686342 bytes
UE4Editor!FEngineLoop::Tick() + 3876 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\launchengineloop.cpp:2214]
UE4Editor!GuardedMain() + 479 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\launch.cpp:131]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.6\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]

Hi Lightning77,

Please post this to the answerhub at http://answers.unrealengine.com so we can assist you in depth. Thank you!