# A DataStore checklist for Roblox beginners: the 8 mistakes that wipe player data

> Source: <https://dev.to/kelvaro/a-datastore-checklist-for-roblox-beginners-the-8-mistakes-that-wipe-player-data-1op1>
> Published: 2026-11-12 17:13:01+00:00

Player data in Roblox rarely disappears because DataStoreService is "broken." It disappears because a save ran with the wrong contents, or did not run at all. The eight mistakes below are the ones I keep seeing in beginner games — and in code that an AI assistant generates on the first try. They are not about leaderboards or monetization. They are about not overwriting a real profile with empty defaults.

This is written for Luau in Roblox Studio, with the current DataStore APIs: `DataStoreService`, `UpdateAsync`, `pcall`, retries, and `BindToClose`. No invented methods. No guarantee that a particular community module will stay unchanged; the patterns stand on their own.

This is the classic wipe.

The server calls `GetAsync` or `UpdateAsync`. The request errors — budget, outage, typo in the store name. The script catches the error and quietly continues with a default table: zero coins, empty inventory. The player moves around for a minute and leaves. You save that default table. Yesterday's progress is gone.

The rule is mechanical: **a session may save only if the load succeeded.** If the load fails after retries, do not let the player into a state that can write. Kick them with a retry message, or keep them in a lobby that cannot trigger a save.

```
local sessions = {} -- [Player]: { loaded: boolean, data: table }

local function canSave(player)
    local session = sessions[player]
    return session ~= nil and session.loaded == true
end
```

Treat "loaded" as a flag you set only after a successful DataStore read, not after you filled in defaults locally.

`GetAsync` plus `SetAsync` instead of `UpdateAsync`
`GetAsync` returns a copy. `SetAsync` writes whatever you hand it. If two servers both load the same player — a trade, a teleport, a rare double session — the slower `SetAsync` wins and the other server's writes vanish.

`UpdateAsync` applies a transform on the latest stored value and retries the transform if the value changed underneath you. Officially, that transform may run more than once and **must not yield**.

```
local DataStoreService = game:GetService("DataStoreService")
local store = DataStoreService:GetDataStore("PlayerData_v1")

local function keyFor(player)
    return "player_" .. player.UserId
end
```

Use `UpdateAsync` for the load (so you can also set a session token) and for the save. Keep `SetAsync` for values that are safe to overwrite blindly, which a full player profile is not.

`nil` from the This one feels like a typo and behaves like a delete.

If the transform function returns `nil`, Roblox **removes the key**. A missed `return data`, a typo, or an early `return` in an error branch will erase the profile. The call can still succeed. You will not get an error that says "deleted."

```
-- Dangerous: a forgotten return deletes the key.
store:UpdateAsync(key, function(old)
    local data = old or { coins = 0 }
    data.coins += 5
    -- missing: return data
end)

-- Correct: always return a table, never nil, unless you intend to delete.
store:UpdateAsync(key, function(old)
    local data = old or { coins = 0 }
    data.coins += 5
    return data
end)
```

Never "clear" a missing field by returning nothing. If `old` is `nil`, that only means the key is new — return a fresh default. Do not return `nil` to mean "leave it unchanged"; if you must abort a write, the documented way is to throw inside the transform so the update is cancelled.

`pcall`, no retries
Every DataStore call can throw. Without `pcall`, one failed request can abort the rest of `PlayerRemoving` and skip the save entirely. With `pcall` but no retry, a single budget blip has the same outcome.

```
local MAX_ATTEMPTS = 5

local function updateWithRetry(key, transform)
    for attempt = 1, MAX_ATTEMPTS do
        local ok, result = pcall(function()
            return store:UpdateAsync(key, transform)
        end)
        if ok then
            return true, result
        end
        warn(("UpdateAsync failed (%s), attempt %d"):format(tostring(result), attempt))
        task.wait(2 ^ (attempt - 1))
    end
    return false, nil
end
```

Use `task.wait`, not `wait()`. The backoff is exponential and stays well under the 30-second `BindToClose` window if you cap the attempts. If the final leave-save still fails, log it and do not pretend it succeeded.

`BindToClose` — or a fight with `PlayerRemoving`
When a server shuts down, players are removed and the instance is killed. `PlayerRemoving` may not get enough time, especially in Studio or during an update. `BindToClose` gives you up to 30 seconds after the close starts. You should save remaining sessions there.

The second half of the bug is running two unsynchronized saves at once. Use a per-player `saving` flag, and only save if `canSave(player)` is true.

```
local Players = game:GetService("Players")
local RunService = game:GetService("RunService")

local function save(player)
    local session = sessions[player]
    if not canSave(player) or session.saving then
        return
    end
    session.saving = true
    local ok = updateWithRetry(keyFor(player), function(old)
        -- Write the in-memory session, which only exists because load succeeded.
        return session.data
    end)
    session.saving = false
    if not ok then
        warn("Final save failed for", player.UserId)
    end
end

Players.PlayerRemoving:Connect(function(player)
    save(player)
    sessions[player] = nil
end)

game:BindToClose(function()
    local leftover = {}
    for _, player in ipairs(Players:GetPlayers()) do
        table.insert(leftover, player)
    end
    for _, player in ipairs(leftover) do
        task.spawn(function()
            save(player)
        end)
    end
    -- In Studio a short wait is usually enough; live servers should wait
    -- until the spawned saves finish or the 30-second limit is close.
    if RunService:IsStudio() then
        task.wait(2)
    else
        task.wait(8)
    end
end)
```

A production version should wait on a counter or a `BindableEvent` instead of a fixed `task.wait(8)`. The point of the snippet is the structure, not a magic number.

`player.Name`
Names change. UserIds do not. A key like `"player_" .. player.Name` looks readable and will silently start a new, empty profile after a rename — or, worse, eventually collide with a name another account used to have.

Always use `player.UserId`. Keep a version suffix on the **store name** (` PlayerData_v1`) when you change the shape of the table, not in a way that depends on the display name.

DataStores have a request budget (you can inspect it with `DataStoreService:GetRequestBudgetForRequestType`). Autosaving every few seconds for every player will spend that budget on writes you do not need. Then the leave-save, the one that actually matters, gets `429` or a budget error and fails.

A practical rhythm is: save on leave, save in `BindToClose`, and autosave on a slow interval (minutes, not seconds), only for sessions that have actually changed. Check the budget before a non-urgent save and skip a cycle rather than blasting retries during an already tight shutdown.

If the character can collect coins before `session.loaded` is true, you will either drop those coins or, if you then save defaults mixed with new rewards, risk writing a half-initialized table. Gate the loop: the player does not receive currency, inventory, or teleports until the session exists.

The related wipe is trusting the client to send the table you store. A RemoteEvent that says "here is my data, please save it" lets an exploiter send an empty inventory — or a full one. The server should already have the session in memory. The client may request an action ("buy this", "equip that"); the server validates, mutates `session.data`, and saves that.

```
local function load(player)
    local ok, data = updateWithRetry(keyFor(player), function(old)
        local profile = old or {
            coins = 0,
            joins = 0,
        }
        profile.joins += 1
        return profile -- never nil
    end)
    if not ok or type(data) ~= "table" then
        player:Kick("Deine Daten konnten nicht geladen werden. Bitte erneut beitreten.")
        return
    end
    sessions[player] = { loaded = true, data = data, saving = false }
end

Players.PlayerAdded:Connect(function(player)
    load(player)
end)
```

Using `UpdateAsync` on load also increments `joins` atomically. If you later add a session lock, put it in this same transform — and release it in the save on leave — instead of inventing a second store.

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