Crash on load due to reference to blueprint generated class

Hi,

I’m running 4.4.2 from the launcher and stumbled across a situation which causes a crash on project load. I was able to work around it but I figured I’d provide my project to the devs to improve engine stability.

In my Settlement blueprint, there’s a function named Start Building Placement. The function has one parameter which is a blueprint generated class (class ‘Building_C’). The intention is to pass in a child class of Building. There’s a call to the function in the Interaction graph.

The bug here is very reproducible. Setting the parameter on the function call (using the dropdown on the function node) to any subclass of Building_C causes the project to crash when next opened. Setting the parameter to None or to Building works fine. I tried creating new blueprint children of Building and they, too, cause a crash on load.

My workaround was just to avoid using a function where I pass in a class Building_C. Passing in a Building object works fine. I know that passing blueprint generated class references as function parameters should work - in fact I’m doing the exact same thing successfully in that same blueprint (passing the class Unit_C). I don’t know what’s wrong with the Building_C class.

Attached is the (rather unhelpful) log and a barebones copy of my project. It’s currently configured to cause the crash on startup, but that can be avoided by removing the Settlement blueprint while the project loads.

Thanks!

Hi dbc221,

I’m getting the crash even with the Settlement blueprint removed. Any ideas what other blueprint maybe causing the crash?

Hmm, removing only that blueprint works for me. No other blueprints are using the same tactic, so I’m not sure what the issue could be. There are a couple native classes that I couldn’t remove, hopefully it’s not them. You could try temporarily removing the whole blueprints folder. At least there’s a reproducible crash, though :slight_smile:

Hi dbc211,

Thank you for the feedback. We will be looking into the issue and if we find the cause we will post back here. We have made several fixes to child/parent blueprints for the next editor release, so this issue may be fixed by then.

TJ

Very much appreciate the update, thanks!