Blueprint Runtime Error: "Accessed None trying to read property CallFunc_Create_ReturnValue"

This error which i have received

can anyone help me with this?

I’m not familiar with UE
I just started learning
Thank you for your time !!!

Blueprint Runtime Error: “Accessed None trying to read property CallFunc_Create_ReturnValue”. Blueprint: ThirdPersonCharacter Function: Takedamage 5% Graph: takedamage5% Node: Add to Viewport