Character is not a valid member of Model "Workspace.TRAINING.Nerd" (remote event)

Question

server:

local FightModule = require(game:GetService("ReplicatedStorage").FightModule)
local remote = game:GetService("ReplicatedStorage").Train

local NPC = script.Parent.Parent.Parent

script.Parent.Triggered:Connect(function(plr)
    remote:FireClient(plr, NPC)
end)

client:

local FightModule = require(game:GetService("ReplicatedStorage").FightModule)
local remote = game:GetService("ReplicatedStorage").Train

remote.OnClientEvent:Connect(function(plr, npc)
    FightModule.TrainFight(plr, npc)
end)

I was trying to sent the player and npc throught the remote event but im getting: Character is not a valid member of Model "Workspace.TRAINING.Nerd"

Answer 1

When using RemoteEvents, the server calls remoteEvent:FireClient(player, a, b, c), but the client will only receive the arguments : remoteEvent.OnClientEvent(function(a, b, c) ...

Your LocalScript code appears to be treating the first argument as the player, when it is actually the NPC sent from the server. Your LocalScript can get the Player object by using game.Players.LocalPlayer.

So try this :

local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local FightModule = require(ReplicatedStorage.FightModule)
local remote = ReplicatedStorage.Train

remote.OnClientEvent:Connect(function(npc)
    FightModule.TrainFight(Players.LocalPlayer, npc)
end)

I'm not sure what your FightModule does, but be careful if you're using it to increment leaderstats counters or anything like that. Changes made on the client will not be replicated back up to the server. If you need stat changes to be seen by all of your players, you might consider moving this code up into the server script.