What are the common pitfalls in async/await?

Question

Accepted Answer

**Async/await pitfalls** — common mistakes to avoid.

**1. async void:**
```csharp
// BAD — fire and forget, exceptions lost
async void Button_Click(object sender, EventArgs e)
{
    await GetDataAsync();  // Exception may be lost!
}

// GOOD — use Task
async Task Button_ClickAsync(object sender, EventArgs e)
{
    await GetDataAsync();
}
```

**2. .Result and .Wait():**
```csharp
// BAD — deadlock!
var data = GetDataAsync().Result;  // Blocks!

// GOOD — async all the way
var data = await GetDataAsync();
```

**3. Not awaiting:**
```csharp
// BAD — fire and forget
GetDataAsync();  // Not awaited!

// GOOD — await
await GetDataAsync();
```

**4. Multiple awaits:**
```csharp
// BAD — sequential
var data = await GetDataAsync();
var users = await GetUsersAsync();

// GOOD — parallel
var dataTask = GetDataAsync();
var usersTask = GetUsersAsync();
await Task.WhenAll(dataTask, usersTask);
```

C#: What are the common pitfalls in async/await?