microsoft/semantic-kernel · error · InvalidOperationException

Failed to start process

Error message

Failed to start process

What it means

Thrown by `DaprTestProcessContext.StartWithEventAsync` when the HTTP POST that starts the process on the Dapr test host (port 5200) returns a non-success status code. The exception carries no body/detail, so the underlying failure (validation error, host error, transport issue) must be inferred from logs. It is an InvalidOperationException.

Solutions

1. Check the Dapr test host logs for the actual error behind the non-success status code.
2. Verify `localhost:5200` is the Dapr process host (not another service) and that it is the expected version.
3. Inspect the serialized `ProcessStartRequest` JSON for null/malformed `Process` or `InitialEvent`.
4. Confirm the process object is valid (non-null Id, resolvable steps) before posting.

Example fix

// before
var response = await this._httpClient.PostAsJsonAsync(url, request);
response.EnsureSuccessStatusCode(); // opaque
// after (surface the body for diagnosis)
var response = await this._httpClient.PostAsJsonAsync(url, request);
if (!response.IsSuccessStatusCode)
{
    var body = await response.Content.ReadAsStringAsync();
    throw new InvalidOperationException($"Failed to start process: {(int)response.StatusCode} {response.StatusCode}: {body}");
}

if (string.IsNullOrWhiteSpace(process?.State?.Id))
    throw new InvalidOperationException("Cannot start a process with no Id via Dapr.");
var request = new ProcessStartRequest { Process = DaprProcessInfo.FromKernelProcess(process), InitialEvent = initialEvent.ToJson() };
if (string.IsNullOrWhiteSpace(request.InitialEvent))
    throw new InvalidOperationException("InitialEvent serialized to null; check initialEvent payload.");

bool IsStartable(KernelProcess p, KernelProcessEvent e) =>
    !string.IsNullOrWhiteSpace(p?.State?.Id) && e is not null;

try { await context.StartWithEventAsync(initialEvent); }
catch (InvalidOperationException ex) when (ex.Message == "Failed to start process")
{
    var body = await lastResponse.Content.ReadAsStringAsync();
    _logger.LogError("Dapr start failed: {Body}", body);
    throw;
}

When it happens

Trigger: POST to `http://localhost:5200/processes/{id}` with a start request whose `Process` or `InitialEvent` is malformed/rejected by the host; the Dapr test host is up but returns 4xx/5xx; the process payload references unknown steps.

Common situations: Dapr runtime/test host running but misconfigured; process serialization mismatch between client and host versions; initial event payload schema mismatch; port conflict putting a different service on 5200.

Related errors

• Process not found
• Dapr Test Host did not start
• A client error occurred while getting search results.
• An unexpected error occurred while getting search results.
• Failed to get search results.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/0f882569e552fefe. Report an issue: GitHub.

Appendix: source

Thrown at dotnet/src/Experimental/Process.IntegrationTestRunner.Dapr/DaprTestProcessContext.cs:50

            TypeInfoResolver = new ProcessStateTypeResolver<KickoffStep>(),
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
        };
    }

    /// <summary>
    /// Starts the process with an initial event.
    /// </summary>
    /// <param name="initialEvent">The initial event.</param>
    /// <returns></returns>
    internal async Task StartWithEventAsync(KernelProcessEvent initialEvent)
    {
        var daprProcess = DaprProcessInfo.FromKernelProcess(this._process);
        var request = new ProcessStartRequest { Process = daprProcess, InitialEvent = initialEvent.ToJson() };

        var response = await this._httpClient.PostAsJsonAsync($"http://localhost:5200/processes/{this._processId}", request, options: this._serializerOptions).ConfigureAwait(false);
        if (!response.IsSuccessStatusCode)
        {
            throw new InvalidOperationException("Failed to start process");
        }
    }

    public override async Task<KernelProcess> GetStateAsync()
    {
        var response = await this._httpClient.GetFromJsonAsync<DaprProcessInfo>($"http://localhost:5200/processes/{this._processId}", options: this._serializerOptions);
        return response switch
        {
            null => throw new InvalidOperationException("Process not found"),
            _ => response.ToKernelProcess()
        };
    }

    public override Task SendEventAsync(KernelProcessEvent processEvent)
    {
        throw new NotImplementedException();
    }

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