microsoft/autogen · error · ArgumentException

Kernel is not running

Error message

Kernel is not running

What it means

Thrown by InteractiveService.SubmitCommandAsync when the internal kernel field is null — the interactive kernel process has not been started (or the service was never given one). All Submit*CodeAsync helpers route through this guard, so any code submission before startup fails with ArgumentException('Kernel is not running').

Source

Thrown at dotnet/src/AutoGen.DotnetInteractive/InteractiveService.cs:62

    public Kernel? Kernel => this.kernel;

    public async Task<bool> StartAsync(string workingDirectory, CancellationToken ct = default)
    {
        if (this.kernel != null)
        {
            return true;
        }

        this.kernel = await this.CreateKernelAsync(workingDirectory, true, ct);
        return true;
    }

    public async Task<string?> SubmitCommandAsync(SubmitCode cmd, CancellationToken ct)
    {
        if (this.kernel == null)
        {
            throw new ArgumentException("Kernel is not running");
        }

        return await this.kernel.RunSubmitCodeCommandAsync(cmd.Code, cmd.TargetKernelName, ct);
    }

    public async Task<string?> SubmitPowershellCodeAsync(string code, CancellationToken ct)
    {
        var command = new SubmitCode(code, targetKernelName: "pwsh");
        return await this.SubmitCommandAsync(command, ct);
    }

    public async Task<string?> SubmitCSharpCodeAsync(string code, CancellationToken ct)
    {
        var command = new SubmitCode(code, targetKernelName: "csharp");
        return await this.SubmitCommandAsync(command, ct);
    }

    public bool RestoreDotnetInteractive()

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Await service.StartAsync(workingDirectory) once before any submit call
2. Check service.Kernel is not null before submitting (it is exposed as a public property) as a cheap pre-condition
3. If the kernel died, recreate the InteractiveService and StartAsync again rather than reusing it
4. Avoid calling submit after DisposeAsync/Dispose

Example fix

// before:
var service = new InteractiveService(dir);
await service.SubmitCSharpCodeAsync("1+1", ct); // throws: kernel null
// after:
var service = new InteractiveService(dir);
await service.StartAsync(workingDirectory);
await service.SubmitCSharpCodeAsync("1+1", ct);

// Guard before submitting
if (service.Kernel is null)
{
    var ok = await service.StartAsync(workingDirectory, ct);
    if (!ok) throw new InvalidOperationException("Failed to start interactive kernel");
}
var result = await service.SubmitCSharpCodeAsync(code, ct);

static bool IsKernelRunning(InteractiveService s) => s.Kernel is not null;

try { await service.SubmitCSharpCodeAsync(code, ct); }
catch (ArgumentException e) when (e.Message == "Kernel is not running")
{ /* kernel not started or died: recreate service, await StartAsync, retry once */ }

When it happens

Trigger: Creating InteractiveService with the directory constructor (kernel starts as null) and calling SubmitCSharpCodeAsync/SubmitPowershellCodeAsync/SubmitCommandAsync before awaiting StartAsync, or after a kernel crash/dispose left kernel null.

Common situations: Forgetting the awaited StartAsync call, calling submit from a thread that races ahead of startup, using the service after Dispose, or the kernel process dying mid-session (then a subsequent submit throws).

Related errors

• InteractiveService is not initialized.
• Installing directory is not set
• Failed to restore dotnet interactive tool.
• The group chat has not been initialized. It must be run befo
• Error initializing: {this.GetType().FullName}; already initi

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/c461d76c81275470. Report an issue: GitHub.