"K2Node_CustomEvent_Weapon" set to none

so im making a multiplayer FPS game for my game dev class and every other play test i’m getting the following error message

Blueprint Runtime Error: “Accessed None trying to read property K2Node_CustomEvent_Weapon”. Node: Set Timer by Event

below is the code where the error occurs; i’d greatly appreciate if anyone can pinpoint what’s causing the bug and/or give fixes.

Looks like Weapon on your RPC is invalid, you should always validate refs which will confirm the error at least.

i see the variable is replicated but it must also be Spawned and Set on server.

option 2 is to not pass it through the RPC at all, this is how cheating happens, the player should just say ‘I want to fire’ and the server will verify it has a weapon