microsoft/semantic-kernel · error · ArgumentException

Unsupported agent type: {agentType}

Error message

Unsupported agent type: {agentType}

What it means

Error "Unsupported agent type: {agentType}" thrown in microsoft/semantic-kernel.

Source

Thrown at dotnet/samples/Demos/A2AClientServer/A2AServer/Program.cs:52

    .AddEnvironmentVariables()
    .AddUserSecrets<Program>()
    .Build();

string? apiKey = configuration["A2AServer:ApiKey"];
string? endpoint = configuration["A2AServer:Endpoint"];
string modelId = configuration["A2AServer:ModelId"] ?? "gpt-4o-mini";

IEnumerable<KernelPlugin> invoicePlugins = [KernelPluginFactory.CreateFromType<InvoiceQueryPlugin>()];

A2AHostAgent? hostAgent = null;
if (!string.IsNullOrEmpty(endpoint) && !string.IsNullOrEmpty(agentId))
{
    hostAgent = agentType.ToUpperInvariant() switch
    {
        "INVOICE" => await HostAgentFactory.CreateFoundryHostAgentAsync(agentType, modelId, endpoint, agentId, invoicePlugins),
        "POLICY" => await HostAgentFactory.CreateFoundryHostAgentAsync(agentType, modelId, endpoint, agentId),
        "LOGISTICS" => await HostAgentFactory.CreateFoundryHostAgentAsync(agentType, modelId, endpoint, agentId),
        _ => throw new ArgumentException($"Unsupported agent type: {agentType}"),
    };
}
else if (!string.IsNullOrEmpty(apiKey))
{
    hostAgent = agentType.ToUpperInvariant() switch
    {
        "INVOICE" => await HostAgentFactory.CreateChatCompletionHostAgentAsync(
            agentType, modelId, apiKey, "InvoiceAgent",
            """
            You specialize in handling queries related to invoices.
            """, invoicePlugins),
        "POLICY" => await HostAgentFactory.CreateChatCompletionHostAgentAsync(
            agentType, modelId, apiKey, "PolicyAgent",
            """
            You specialize in handling queries related to policies and customer communications.
            
            Always reply with exactly this text:
            

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Pass a supported agent type via configuration or command line; review Program.cs for the list of valid values.
2. Fix typos in the agent type value so it matches a supported type exactly.

When it happens

Trigger: Thrown at dotnet/samples/Demos/A2AClientServer/A2AServer/Program.cs:52 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/bfb0bebe018cc2de. Report an issue: GitHub.