Error: Accessed none from node Set Value as Bool

Hey, I get error Accessed None ‘CallFunc_getBlackboard_ReturnValue’ from node Set Value as Bool in graph ‘EventGraph’ in blueprint PCSCharacter

I was following tutorial: - YouTube

I know it is older version, but so far it proved to be what i was looking for.

Problem is somewhere near changing boolean attribute called IsChasing.
This attribute is defined in blackboard and i needed to change it to true in my NPC character (blueprint class).
But I think you cant access it by tag like Set(attribute) to true because it is defined in that blackboard (probably).

So by following tutorial i get this:

Variable in make literal name is called precisely like the refered to one.

When i create 1 NPC no problem occures, but when i create 7 NPC behavior tree start to act funny and switch without triggering NPC by box.

When i debugged i was that boolean variable IsChasing is changing on its own, sometimes(with multiple npc)…
I am sure i am not in any of triggering boxes, I have them visible…
Any idea how to fix this?

behavior tree:

Thx for help

I was not checking what i was writing, sorry for some strange sentences :smiley:

Ok i know now why IsChasing do change now, it is because too many NPC near each other trigger boxes around them, but still cant find why is that error happening

Couple of things to ponder here. The first is that you might want to use EQS/Perception instead of objects that overlap things for sight but depending on your purposes this might be what you need, just a thought.

The other thing is you should turn on the blueprint feature to break on exceptions. See this question on how to enable it: How to break Blueprint execution on "Accessed None"? - Debugging, Optimization, & Profiling - Epic Developer Community Forums

What might be happening is the blackboard isn’t set before it’s called and you are accessing none. Could try to put a breakpoint on both of those set nodes and see what the issue is as well, just right click on the node and there is an option to set a breakpoint or select the node(s) and press F9. Once you hit a breakpoint you can hover over many of the pins and it will show you the value.

Hi, i followed instructions in that link and it paused my project in place where i knew it would pause. U are probably right with that whole blackboard thing…
Thx for that EQS/Perseption tip. I will try it now. I did not like that overlap as well but it was used in tutorial i was watching so i did it as well.

Thx for your time writing answer.

I am not sure I entirely follow what you’re doing. If you want more specific help, it may be a good idea to upload entire blueprint for us to have a look at.

A couple of things that jump out at me:

  1. If you are trying to set Boolean value on the Blackboard, you need to use Set Blackboard Value as Bool - not what you are using right now. I don’t see how what you have would work.
  2. “Error Access None” usually means you’re not performing validation (look into isValid) or sometimes it means you haven’t declared something as a public variable.

Try those two things and let us know how you went

For anyone having this Error “Accessed None ‘CallFunc_getBlackboard_ReturnValue’ from node Set Value as Bool in graph ‘EventGraph’ in blueprint PCSCharacter” The FIX is the Box you made can not be inside the NPC so move it out side of it. This is what fixed my problem.

For anyone having this Error “Accessed None ‘CallFunc_getBlackboard_ReturnValue’ from node Set Value as Bool in graph ‘EventGraph’ in blueprint PCSCharacter” The FIX is the Box you made can not be inside the NPC so move it out side of it. This is what fixed my problem.