microsoft/autogen · error · Exception

Please set OPENAI_API_KEY environment variable.

Error message

Please set OPENAI_API_KEY environment variable.

What it means

Guard in OpenAICodeSnippet.CreateOpenAIChatAgentAsync: OPENAI_API_KEY is null, so it throws before OpenAIClient(openAIKey) is constructed (an empty/invalid key would otherwise surface later as an OpenAI SDK auth error). This snippet builds an OpenAIChatAgent on gpt-4o-mini.

Source

Thrown at dotnet/samples/AgentChat/AutoGen.Basic.Sample/CodeSnippet/OpenAICodeSnippet.cs:35

    [Function]
    public async Task<string> GetWeather(string location)
    {
        return "The weather in " + location + " is sunny.";
    }
}
#endregion weather_function
public partial class OpenAICodeSnippet
{
    [Function]
    public async Task<string> GetWeather(string location)
    {
        return "The weather in " + location + " is sunny.";
    }

    public async Task CreateOpenAIChatAgentAsync()
    {
        #region create_openai_chat_agent
        var openAIKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") ?? throw new Exception("Please set OPENAI_API_KEY environment variable.");
        var modelId = "gpt-4o-mini";
        var openAIClient = new OpenAIClient(openAIKey);

        // create an open ai chat agent
        var openAIChatAgent = new OpenAIChatAgent(
            chatClient: openAIClient.GetChatClient(modelId),
            name: "assistant",
            systemMessage: "You are an assistant that help user to do some tasks.");

        // OpenAIChatAgent supports the following message types:
        // - IMessage<ChatRequestMessage> where ChatRequestMessage is from Azure.AI.OpenAI

        var helloMessage = new UserChatMessage("Hello");

        // Use MessageEnvelope.Create to create an IMessage<ChatRequestMessage>
        var chatMessageContent = MessageEnvelope.Create(helloMessage);
        var reply = await openAIChatAgent.SendAsync(chatMessageContent);

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Export OPENAI_API_KEY and rerun; verify with echo $OPENAI_API_KEY.
2. Add the variable to the CI pipeline secrets or launchSettings.json for IDE runs.
3. Load a .env file at startup if the project supports it.
4. Restart the process after setting the variable.

if (string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable("OPENAI_API_KEY")))
{
    Console.Error.WriteLine("Please set OPENAI_API_KEY environment variable.");
    return;
}

When it happens

Trigger: Running the OpenAI chat-agent snippet (or its executing test) without OPENAI_API_KEY in the process environment.

Common situations: Fresh environment without the key exported; snippet executed by doc tests in CI lacking the secret; key set in a different shell session.

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 ANTHROPIC_API_KEY environment variable.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/994ee42c6b706c5f. Report an issue: GitHub.