microsoft/aspire · error · InvalidOperationException

Cannot complete step: Reporter is not set.

Error message

Cannot complete step: Reporter is not set.

What it means

ReportingStep.CompleteAsync(string, CompletionState, CancellationToken) throws InvalidOperationException when Reporter is null. Completing a step requires forwarding the completion text and state to the reporter; without one the step cannot report completion. The step must be wired to a reporter for its whole lifetime.

Solutions

1. Create and complete the step through the pipeline infrastructure so Reporter is always attached.
2. Assign a valid reporter before calling CompleteAsync.
3. Guard on Reporter is null before completing, or use a try/finally with a reporter-availability check.
4. In tests, register a fake reporter implementation.

Example fix

// before
await step.CompleteAsync("Deployment finished", CompletionState.Completed);

// after
if (step.Reporter is null)
{
    throw new InvalidOperationException("Attach a reporter to the step before completing it.");
}
await step.CompleteAsync("Deployment finished", CompletionState.Completed);

if (step.Reporter is null)
{
    throw new InvalidOperationException("Step has no reporter; cannot complete.");
}

bool canComplete = step.Reporter is not null;

try
{
    await step.CompleteAsync(completionText, state);
}
catch (InvalidOperationException ex) when (ex.Message.Contains("Reporter is not set"))
{
    logger.LogError(ex, "Step completion skipped: no reporter attached.");
}

When it happens

Trigger: Calling await step.CompleteAsync("Done", CompletionState.Completed) on a ReportingStep whose Reporter property was never assigned or has been cleared.

Common situations: Manually constructed steps in tests, custom pipeline code completing steps after pipeline context teardown, or steps created outside the standard pipeline API.

Understand the failure class

Background: "not installed", "pip install", "required for": how missing-dependency errors surface across open-source libraries — this error's family across 34 libraries.

Related errors

• Cannot create task: Reporter is not set.
• Value cannot be null. (Parameter 'key')
• Value cannot be null. (Parameter 'value')
• Cannot complete task
• Cannot create task for step

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/90acacb8d1e2e7b9. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/Pipelines/ReportingStep.cs:171

    /// <inheritdoc />
    public void Log(LogLevel logLevel, MarkdownString message)
    {
        ArgumentNullException.ThrowIfNull(message);

        if (Reporter is null)
        {
            return;
        }

        Reporter.Log(this, logLevel, message.Value, enableMarkdown: true);
    }

    /// <inheritdoc />
    public async Task CompleteAsync(string completionText, CompletionState completionState = CompletionState.Completed, CancellationToken cancellationToken = default)
    {
        if (Reporter is null)
        {
            throw new InvalidOperationException("Cannot complete step: Reporter is not set.");
        }

        await Reporter.CompleteStepAsync(this, completionText, completionState, enableMarkdown: false, cancellationToken: cancellationToken).ConfigureAwait(false);
    }

    /// <inheritdoc />
    public async Task CompleteAsync(MarkdownString completionText, CompletionState completionState = CompletionState.Completed, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(completionText);

        if (Reporter is null)
        {
            throw new InvalidOperationException("Cannot complete step: Reporter is not set.");
        }

        await Reporter.CompleteStepAsync(this, completionText.Value, completionState, enableMarkdown: true, cancellationToken: cancellationToken).ConfigureAwait(false);
    }

View on GitHub (pinned to 25830f84bd)