microsoft/autogen · error · Exception

Please set OPENAI_API_KEY environment variable.

Error message

Please set OPENAI_API_KEY environment variable.

What it means

Startup guard in the Dynamic Group Chat getting-started sample: RunAsync reads OPENAI_API_KEY and throws a plain Exception when absent, because OpenAIClient(apiKey) cannot be constructed for the coder/other chat agents without it. The throw is sample-authored and fires before any agent or group-chat scaffolding is built.

Source

Thrown at dotnet/samples/AgentChat/AutoGen.Basic.Sample/GettingStart/Dynamic_Group_Chat.cs:18

// Copyright (c) Microsoft Corporation. All rights reserved.
// Dynamic_Group_Chat.cs

using AutoGen.Core;
using AutoGen.OpenAI;
using AutoGen.OpenAI.Extension;
using AutoGen.SemanticKernel;
using AutoGen.SemanticKernel.Extension;
using Microsoft.SemanticKernel;
using OpenAI;

namespace AutoGen.Basic.Sample;

public class Dynamic_Group_Chat
{
    public static async Task RunAsync()
    {
        var apiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") ?? throw new Exception("Please set OPENAI_API_KEY environment variable.");
        var model = "gpt-4o-mini";

        #region Create_Coder
        var openaiClient = new OpenAIClient(apiKey);
        var coder = new OpenAIChatAgent(
            chatClient: openaiClient.GetChatClient(model),
            name: "coder",
            systemMessage: "You are a C# coder, when writing csharp code, please put the code between ```csharp and ```")
            .RegisterMessageConnector() // convert OpenAI message to AutoGen message
            .RegisterPrintMessage(); // print the message content
        #endregion Create_Coder

        #region Create_Commenter
        var kernel = Kernel
            .CreateBuilder()
            .AddOpenAIChatCompletion(modelId: model, apiKey: apiKey)
            .Build();
        var commenter = new SemanticKernelAgent(

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Set OPENAI_API_KEY (export on bash, $env:/setx on Windows) in the environment that launches the sample.
2. Add the key to your IDE's debug environment profile if you run the sample from Visual Studio/Rider.
3. Verify the process actually sees the variable (quick console print) — dotnet does not load .env automatically.
4. Ensure the key has gpt-4o-mini access, since the sample hard-codes that model.

Example fix

// before
var apiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") ?? throw new Exception("Please set OPENAI_API_KEY environment variable.");

// after
var apiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY")
    ?? throw new InvalidOperationException("OPENAI_API_KEY is not set. Export it before running Dynamic_Group_Chat.");

var apiKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY");
if (string.IsNullOrWhiteSpace(apiKey))
{
    Console.Error.WriteLine("Set OPENAI_API_KEY before running Dynamic_Group_Chat.");
    return;
}

try
{
    await Dynamic_Group_Chat.RunAsync();
}
catch (Exception ex) when (ex.Message.Contains("OPENAI_API_KEY"))
{
    Console.Error.WriteLine($"Configuration error: {ex.Message}");
}

When it happens

Trigger: Invoking Dynamic_Group_Chat.RunAsync() with OPENAI_API_KEY unset or empty in the launching process. It fails at the first line, before the coder OpenAIChatAgent is created.

Common situations: New users following the getting-started docs but skipping the API-key setup step; running samples in CI without OpenAI secrets; the variable set in a parent shell but the sample launched from a fresh terminal or IDE.

Related errors

• Please set OPENAI_API_KEY environment variable.
• Please set OPENAI_API_KEY environment variable.
• Please set OPENAI_API_KEY environment variable.
• Please set OPENAI_API_KEY environment variable.
• Please set OPENAI_API_KEY environment variable.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/f84b70b714b3bb14. Report an issue: GitHub.