Setting Custom Event To Multicast Causes Crash

I am trying to replicate a function that calls AI animations from the server to clients. All the AI units are based on the superclass BaseUnit Base unit has the custom event EnemyFound_Event. Inside the base unit class, this event does nothing.

Every unit subclassing base unit implements this event by adding the Event Enemy Found Event to the event graph. Because these are inherited events, I can’t change them in the individual subclasses. When I go to change the EnemyFound_Event in BaseUnit The engine crashes. Please review the full crash logs and let me know what I can do to fix this.

Repo Steps

  1. Create a new blueprint Called Test
  2. Create a custom event in Test called My_Event
  3. Save and compile Test
  4. Right click the Test blueprint and chose Create blueprint based on this
  5. Inside Test_Child add the Event My Event event to the event graph
  6. connect Event My Event to a print node.
  7. Save and compile Test_Child
  8. Open the Test blueprint
  9. Select the My_Event custom event and change it to multicast.
  10. Compile Test
  11. Engine crashes here.

Hi Justin,

Thank you for the feedback. I was able to reproduce your crash and I have submitted this as JIRA report UE-5444 in our tracking software. Our developers will be looking into this further.

Unfortunately I don’t have a workaround for you at this time. If you make the event multicast in the parent first, then create the child. The reference for the event in the child will have this error.

“Function’s net flags don’t match parent function’s flags”.

This is also a known issue that is being looked into at the moment and is JIRA report UE-3289 in our system.

Cheers,

TJ

Alright I’ll see what I can do to determine a work around on my end. Not being able to replicate overloaded events seems like a major issue though. Is it a possibility that we might see it in 4.6 or is it simply not within the realm or possibility at this time?

It’s very doubtful the fix will make it into 4.6., but it is possible you could see it as early as 4.7. Finding a crash bug like you did is quite helpful and should expedite the process a bit.

Thanks. If that’s the case I will look into changing the way the system works so as to not inherit from a parent class.

Is there any update on this? I’m trying to use toggleable powerups with a parent child structure and I can’t seem to find a way to get it working without custom events.

hi there,

i just submitted a fix that should address both the crash (assert) and the compile error on the child Blueprint.

change # 2375121 (in Perforce)
-or-
GitHub link:
=> https://github.com/EpicGames/UnrealEngine/commit/0b35b1015aa9b381ba3beceee423662af055c5ce

hope this helps!