Unreal gives error when line tracing collision

Question

I am currently using Unreal Engine 4.26. I have been following this tutorial to make a parkour game in Unreal.

I followed the tutorial exactly, and made a walk/jump/double jump game.

However, when I made the wall climbing system, Unreal started giving an error.

The wall climbing still works, but it shows this error when it ends:

Blueprint Runtime Error: "Accessed None trying to read property CallFunc_BreakHitResult_HitActor". Blueprint:  Parkour_BP_Char Function:  Execute Ubergraph Parkour BP Char Graph:  EventGraph Node:  Branch

It has hundreds of copies of that error in the message log.

I would provide my unreal file, but I don't know how.

Here is the double jump blueprint setup; Image 1 Image 2 Image 3

(Sorry about 3 images, it's a large setup.)

Does anyone know how I can solve the error?

Will edit question with more info if needed.

Answer 1

The error is caused because your linetrace isn't hitting anything but is still trying to run the rest of the code.

To prevent this, there is a node called "Is Valid"

Actually, there's two of them. One of them is an executable and handles what happens if the node is valid and isn't, the other ends with a Boolean and you need a branch. Plug the Hit Hit Actor into the node to check if it is valid.

If you use one of these between your hit result and the branch that your "Actor Has Tag" is going in to, this should fix the error.