Accessd none trying to read property "Error"

I am trying to read the array from the actor Default Points and assigning it to the array Way Point List, but it gives me this error"Accessd none trying to read property".

This is my blueprint

Thanks in advance.:o

“Accessed None” means you are trying to get data from a pointer/reference (blue colored variable) while it’s empty.
If you connect that “DefaultPoints” to the IsValid node, it should print “not valid”.

How to fix?

Fill the variable with the reference of the “DefaultPoints” actor.

Where do I get this from?

You need a spawned Instance of it somewhere. (Or created Instance if it’s an Object).
Either you spawn it by just dragging it into the scene or you spawn it from code (Node: Spawn Actor).
Spawning it from code would give you the reference as the return value.
If you spawn it by dragging it into the level you have to tricks a bit (which is not really ideal but you COULD use it).

There is a node called “GetAllActorsOfClass”. I really dislike it!, because it’s kinda lazy and bad programming, but it returns you an Array of spawned Actors of the specified class.
You could use that to get the Index (0) of the Array which should be your Actor that you spawned by dragging it into the level.

What would be a better way of doing it?

Your actor has a BeginPlay function too. UE4 features a few Actors that you can easy reference, such as “GameState”, “GameMode”, “PlayerState”, “PlayerCharacter/Pawn”, “PlayerController”.
I don’t know in which Actor you are working here (your screenshot), but assuming it is one of the mentioned actors above, you should do it other way round.

Go into the DefaultPoints Actor and on BeginPlay, use “Get…” (e.g. GetGameState) to get what ever Actor you are using currently (screenshot). Then cast it ot your custom class of it and set the Array like this.
That’s a way better way of doing it!

What if I don’t use one of the listed Actors in my Screenshot?

Then you are working with some custom Actor that you probably also Spawn at some point.
If you spawn it ALSO by dragging it into the scene, you can set the “DefaultPoints” variable to “Editable” and assign the reference by simply clicking on the instance of the screenshot actor and checking its details on the right side of the editor.
In there you can then select your DefaultPoints actor.

If, however, you spawn the Actor at some point, you would need to think about a good way of Spawning it while directly passing it the DefaultPoints actor.

You can combine the mentioned methods.

Technically there should NEVER be a point at which you really need the “GetAllActorsOfClass” node.