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.

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();
    }

View on GitHub (pinned to c028a0c7dc)

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
• This method is not implemented in this test fixture.
• The Map must be initialized before accessing the Name proper
• The process cannot be started before it has been initialized

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