What causes "Current count is too big!" in dotnet/AspNetCore.Docs?

Recognize this is sample code: to stop the throw, either remove the if-block or raise the threshold.

dotnet/AspNetCore.Docs · error · InvalidOperationException

Current count is too big!

Error message

Current count is too big!

What it means

This is intentionally-thrown demo code. The Counter component throws InvalidOperationException("Current count is too big!") once currentCount exceeds 5. The sample exists to demonstrate Blazor's default unhandled-exception behavior (the developer-exception page in Development, or the error UI in Production) for interactive server components. It is not a library error; it is a teaching throw.

Source

Thrown at aspnetcore/blazor/fundamentals/handle-errors.md:285

`EmbeddedCounter.razor`:

```razor
<h1>Embedded Counter</h1>

<p role="status">Current count: @currentCount</p>
<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;

        if (currentCount > 5)
        {
            throw new InvalidOperationException("Current count is too big!");
        }
    }
}
```

`Home.razor`:

```razor
@page "/"
@rendermode InteractiveServer

<PageTitle>Home</PageTitle>

<h1>Home</h1>

<ErrorBoundary>
    <EmbeddedCounter />
</ErrorBoundary>

View on GitHub (pinned to c67a80103a)

Solutions

Recognize this is sample code: to stop the throw, either remove the if-block or raise the threshold.
If learning error handling, add an <ErrorBoundary> around the component to catch the rendered exception gracefully.
If you copied this into real code by mistake, replace the artificial check with real domain validation.
For production, never throw on a benign counter overflow — return early or cap the value instead.

Example fix

// before
if (currentCount > 5)
{
    throw new InvalidOperationException("Current count is too big!");
}

// after — cap instead of throwing
if (currentCount > 5)
{
    currentCount = 5;
    return;
}

Defensive patterns

Strategy: validation

Validate before calling

// Prevent the demo throw by capping before increment
if (currentCount >= 5) { return; }
currentCount++;

Try / catch

<ErrorBoundary> @* wrap component so throw is caught *@
    <ChildComponent />
    <ChildContent>...</ChildContent>
</ErrorBoundary>

Prevention

Do not ship demo thresholds in production code.
Wrap interactive components in <ErrorBoundary>.
Replace artificial throws with real domain validation.
Cap input-driven values rather than throwing.

When it happens

Trigger: Clicking the 'Click me' button more than 5 times in a row in the sample Counter/Home component. Each IncrementCount increments currentCount; on the 6th click the condition (currentCount > 5) becomes true and the exception is thrown.

Common situations: Running the docs sample locally and clicking past 5; copying the sample into your own app to learn Blazor error boundaries. Not a production condition — the message is illustrative.

Related errors

AI-assisted analysis of dotnet/AspNetCore.Docs@c67a80103a (2026-08-13). Data as JSON: /api/errors/864a092a711b452c. Report an issue: GitHub.