MS Foundry X Agent Framework: GetAgentAsync fails with "The requested operation requires an element of type 'Object', but the target element has type 'Array'"

Question

MS Foundry X Agent Framework: GetAgentAsync fails with "The requested operation requires an element of type 'Object', but the target element has type 'Array'"

Jason Lee 226

Hi,

I'm using a simplified version of the official code example for using a MS Foundry agent from a Web API. More specifically, my end goal is to get a MS Foundry Agent to work with Agent Framework as a function tool like in this example which is for the older AI Foundry. When I try to retrieve the agent using GetAgentAsync (i.e. first line in my GetFunction method), I get the error System.InvalidOperationException: 'The requested operation requires an element of type 'Object', but the target element has type 'Array'.' Here's my code. Am I doing this properly?

public class WeekendPlannerAgent
{
    private readonly IConfiguration _configuration;
    private readonly ILogger<WeekendPlannerAgent> _logger;
    private readonly AIProjectClient _projectClient;

    public WeekendPlannerAgent(IConfiguration configuration, ILogger<WeekendPlannerAgent> logger)
    {
        _configuration = configuration;
        _logger = logger;

        _projectClient = new AIProjectClient(
        new Uri("https://---.services.ai.azure.com/api/projects/----"),
        new DefaultAzureCredential());
    }

    public async Task<AIFunction> GetFunction()
    {
        AgentRecord agentRecord = await _projectClient.Agents.GetAgentAsync("weekend-planner");
        var agentVersion = agentRecord.Versions.Latest;
        var responseClient = _projectClient.OpenAI.GetProjectResponsesClientForAgent(agentVersion);
        var chatClient = responseClient.AsIChatClient();
        var agent = chatClient.CreateAIAgent();
        return agent.AsAIFunction();
    }
}

I have deployed the agent as shown here. User's image

Here's relevant dependencies in my .csproj.

    <PackageReference Include="Azure.AI.Projects" Version="1.2.0-beta.4" />
    <PackageReference Include="Microsoft.Agents.AI.AzureAI" Version="1.0.0-preview.251125.1" />

The official code example doesn't show what I should use for agent ID, is mine correct? In the deprecated AI Foundry, it was a random series of numbers prefixed by "asst_", but I don't see that in the new MS Foundry.

This may be related to the same root cause (bug?) as in my other post since the error is the same, but in completely different context/scenario.

Also feel free to tell me I'm integrating this MS Foundry agent incorrectly with Agent Framework.

Thanks in advance!

1 answer

Your answer

Answer 1

Gowtham CP 6,920 Volunteer Moderator

Hi Jason Lee ,

Thank you for reaching out on the Microsoft Q&A forum.

To retrieve your agent using GetAgentAsync, please ensure you are using the Agent ID (GUID) from the Azure AI Foundry portal:

Azure AI Foundry → Project → Agents → Select Agent → Agent Details → Agent ID

Then update your code as follows:

string agentId = "<your-agent-id>";
AgentRecord agentRecord = await _projectClient.Agents.GetAgentAsync(agentId);

var agentVersion = agentRecord.Versions.Latest;
var responseClient = _projectClient.OpenAI.GetProjectResponsesClientForAgent(agentVersion);

var chatClient = responseClient.AsIChatClient();
var agent = chatClient.CreateAIAgent();
return agent.AsAIFunction();

Please also confirm that the agent version is published and deployed within your AI Project.

References:

Azure AI Foundry — Agents Overview https://learn.microsoft.com/en-us/azure/ai-foundry/agents/overview

Quickstart — Create an Agent in Azure AI Foundry https://learn.microsoft.com/en-us/azure/ai-foundry/agents/quickstart

Microsoft Agent Framework — Azure AI Foundry Agent https://learn.microsoft.com/en-us/agent-framework/user-guide/agents/agent-types/azure-ai-foundry-agent

I hope this helps!

If the information is useful, please accept the answer and upvote it to close the thread. Thanks.

Jason Lee 226 Reputation points

2025-12-04T14:24:24.07+00:00

Thanks @Gowtham CP for the reply, but your answer is for the "classic" AI Foundry. I'm trying to use the new Microsoft Foundry preview and it doesn't have the same ID field as you can see from my screenshot. When I open the YAML generated for the agent, the ID is not the "asst_#####" like it is in AI Foundry since it's now the name of the agent concatenated to the version number as per this screenshot.

I've tried both "weekend-planner" and "weekend-planner:1" as the ID, but neither work.
Gowtham CP 6,920 Reputation points Volunteer Moderator

2025-12-05T08:45:35.78+00:00
Hi Jason Lee ,

Got it — since you’re working with Foundry Classic, the correct ID is the one shown in the Classic Foundry portal, just like in the quickstart. Classic agents use a different identity model, and the preview-style name/version YAML isn’t used there.

To avoid the “expected Object but found Array” error, the safest approach is to let the SDK give you the exact agent ID that Classic expects. You can do that with:

await foreach (var agent in _projectClient.Agents.GetAgentsAsync()) { Console.WriteLine(agent.Value.Id); }

Then pass that ID into:

var agentRecord = await _projectClient.Agents.GetAgentAsync(agentId);

This ensures you're using the correct Classic identifier format and resolves the deserialization issue.

Reference (Classic quickstart): https://learn.microsoft.com/en-us/azure/ai-foundry/quickstarts/get-started-code?view=foundry-classic&tabs=csharp%2Cpython2

Happy to help further if you want to inspect the returned agent metadata.,
Jason Lee 226 Reputation points

2025-12-05T13:51:49.7333333+00:00

Hi @Gowtham CP , thanks for the reply. Sorry, I think you misunderstand. I'm trying to use the NEW Microsoft Foundry with the beta Azure.AI.Projects, not the old AI Foundry (aka Classic MS Foundry). To recap, I can't figure out how to GetAgentAsync to work as I get an error using code similar to the official MS example.

Share via

MS Foundry X Agent Framework: GetAgentAsync fails with "The requested operation requires an element of type 'Object', but the target element has type 'Array'"

1 answer

Your answer