If you've been banging your head against a wall trying to get a roblox remote function script return to actually pass data back to your local script, you aren't alone. It's one of those things in Luau that looks simple on paper but can easily break your game if you don't handle the "handshake" between the client and the server correctly. Unlike a standard RemoteEvent, which is basically just shouting into a megaphone and hoping someone hears you, a RemoteFunction is more like a phone call—you're expecting an answer on the other end.
When we talk about the return value, we're talking about that specific moment when the server finishes its task and sends a piece of information back to the client that asked for it. It could be a boolean to confirm a purchase, a string containing a player's rank, or even a table of inventory items. Whatever it is, if that return isn't handled right, your local script is just going to sit there "yielding" (waiting) forever, and your UI will probably freeze up.
Why Use a RemoteFunction Instead of an Event?
Most of the time, we use RemoteEvents because they're fast and they don't hold up the rest of the code. You fire it and forget it. But sometimes, you need that data back immediately.
Let's say a player clicks a button to buy a new sword. If you use a RemoteEvent, the client tells the server "I want this sword," and the server processes it. But the client has no idea if it actually worked unless the server fires another event back. That's messy. With a roblox remote function script return, the client asks "Can I buy this?" and the server immediately replies "Yes" or "No." It keeps your code much cleaner because the logic stays in one sequential block.
Setting Up the Script and the Function
First things first, you've got to put your RemoteFunction in a place where both the server and the client can see it. ReplicatedStorage is the standard spot for this. If you put it in ServerStorage, your LocalScript won't be able to find it, and you'll get those annoying "infinite yield" warnings in the output.
The Client-Side Call
On the client side (your LocalScript), you use InvokeServer(). This is the trigger. The moment this line runs, the LocalScript pauses. It's waiting for the server to do its thing and send something back.
```lua local ReplicatedStorage = game:GetService("ReplicatedStorage") local myRemoteFunction = ReplicatedStorage:WaitForChild("CheckPointsFunction")
local playerPoints = myRemoteFunction:InvokeServer() print("The server says I have " .. playerPoints .. " points!") ```
Notice how playerPoints is set directly to the result of InvokeServer(). This is where the magic happens. But for this to work, the server has to be set up to actually give that data back.
The Server-Side Logic
On the server (a regular Script in ServerScriptService), you don't "connect" to a RemoteFunction like you do with an event. Instead, you assign a function to OnServerInvoke. This is a huge distinction that trips up a lot of beginners.
```lua local ReplicatedStorage = game:GetService("ReplicatedStorage") local myRemoteFunction = Instance.new("RemoteFunction") myRemoteFunction.Name = "CheckPointsFunction" myRemoteFunction.Parent = ReplicatedStorage
myRemoteFunction.OnServerInvoke = function(player) -- Do some logic here, like checking a DataStore local points = 50 -- Let's pretend we fetched this
return points -- This is the roblox remote function script return end ```
The return points line is what sends the data back down the pipe to the client. Without that return, the client-side script will just stay paused, waiting for an answer that's never coming.
Handling the "Yielding" Problem
One thing you've got to be careful about is that InvokeServer() is synchronous. That's a fancy way of saying it stops everything in that script until it gets a response. If your server-side script is slow—maybe it's waiting for a response from an external API or a slow DataStore—the player's local script is just going to hang.
If you're running this inside a UI loop or something critical, a slow roblox remote function script return can make your game feel laggy. To avoid this, you should always make sure your server-side logic is as fast as possible. If the server script errors out or the player leaves while the function is running, the client might wait forever.
It's often a good idea to wrap your InvokeServer() in a pcall (protected call). This way, if something goes wrong on the server, your client script doesn't just die; it can handle the error gracefully and maybe show a "Try again later" message to the player.
Security is Not Optional
Here is where a lot of people mess up. Because the client is the one starting this "conversation," you can't trust the data they send. Even though we're focused on the roblox remote function script return, the data going to the server is just as important.
Never let the client tell the server what the return value should be. For example, if you have a RemoteFunction called GetPrice, don't let the client pass the name of the item and the price they think it is. The client should only send the item name, and the server should look up the price in its own internal table.
If you trust the client, a hacker can easily intercept that call and tell your script "The price of this 10,000 Robux item is actually 0," and your script will happily return that value and process the transaction. Always do your "sanity checks" on the server before you return any data.
When to Avoid RemoteFunctions
Believe it or not, you don't always want a roblox remote function script return. If you're trying to send data from the server to the client and you need a return from the player, you should probably rethink your architecture.
Roblox actually discourages using InvokeClient(). Why? Because if the player's internet is bad, or if they're using a cheat to purposely ignore the request, your server script will hang indefinitely. A hung server script is much worse than a hung local script. If the server stops, it can break the game for everyone.
If you absolutely need data from a client, it's much safer to use two RemoteEvents. One to ask the client for data, and another for the client to send it back. It's a bit more work to code, but it prevents your server from ever getting stuck.
Common Bugs to Look Out For
If your roblox remote function script return is giving you nil or an error, check these three things:
- The Player Argument: On the server, the first argument of
OnServerInvokeis always theplayerwho called it. Even if you don't send any arguments from the client, thatplayerobject will still be there. If you forget this and try to use your first custom argument, everything will be shifted over, and your logic will break. - Returning Nothing: If you have an
ifstatement on your server and only return a value inside thatifblock, what happens if the condition isn't met? The function returnsnil. Your client script needs to be ready to handle anilreturn. - Defining the Callback Too Late: If the client invokes the function before the server has actually defined
OnServerInvoke, the call will fail. Always make sure your server-side RemoteFunction setup happens early in the script execution.
Wrapping It Up
Using the roblox remote function script return correctly makes your game's communication way more efficient. It's the best way to handle "request-response" logic where the client needs a quick answer to move forward. Just remember to keep your server logic tight, never trust the client's input, and always account for the fact that a return might take a second or two if the server is busy.
Once you get the hang of it, you'll find that your scripts are much more organized, and you'll spend way less time trying to coordinate multiple RemoteEvents just to get a simple "Yes" or "No" from the server. Happy scripting!