microsoft/autogen · error · Exception

Please set OPENAI_API_KEY environment variable.

Error message

Please set OPENAI_API_KEY environment variable.

What it means

Thrown by the 'Create_Semantic_Kernel_Chat_Agent' sample when OPENAI_API_KEY is missing. This sample builds a Microsoft.SemanticKernel Kernel and wraps Semantic Kernel's built-in ChatCompletionAgent, and the key is required by AddOpenAIChatCompletion before any agent runs. The guard makes the missing-configuration failure explicit at startup.

Source

Thrown at dotnet/samples/AgentChat/AutoGen.SemanticKernel.Sample/Create_Semantic_Kernel_Chat_Agent.cs:16

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

#region Using
using AutoGen.Core;
using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.Agents;
#endregion Using
namespace AutoGen.SemanticKernel.Sample;

public class Create_Semantic_Kernel_Chat_Agent
{
    public static async Task RunAsync()
    {
        #region Create_Kernel
        var openAIKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY") ?? throw new Exception("Please set OPENAI_API_KEY environment variable.");
        var modelId = "gpt-3.5-turbo";
        var kernel = Kernel.CreateBuilder()
            .AddOpenAIChatCompletion(modelId: modelId, apiKey: openAIKey)
            .Build();
        #endregion Create_Kernel

        #region Create_ChatCompletionAgent
        // The built-in ChatCompletionAgent from semantic kernel.
        var chatAgent = new ChatCompletionAgent()
        {
            Kernel = kernel,
            Name = "assistant",
            Description = "You are a helpful AI assistant",
        };
        #endregion Create_ChatCompletionAgent

        #region Create_SemanticKernelChatCompletionAgent
        var messageConnector = new SemanticKernelChatMessageContentConnector();

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Set OPENAI_API_KEY in the launching shell: export OPENAI_API_KEY=sk-... or $env:OPENAI_API_KEY='sk-...'.
2. Persist the variable (setx on Windows, shell rc file on Unix) and restart the IDE/terminal.
3. Put it in Properties/launchSettings.json environmentVariables for IDE debugging.
4. Verify with: echo $OPENAI_API_KEY (should print sk-...) before rerunning.

Example fix

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

// after
var openAIKey = Environment.GetEnvironmentVariable("OPENAI_API_KEY")
    ?? throw new InvalidOperationException("OPENAI_API_KEY is not set; export it or configure it in launchSettings.json.");

string[] required = { "OPENAI_API_KEY" };
var missing = required.Where(v => string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable(v))).ToArray();
if (missing.Length > 0) { Console.Error.WriteLine($"Missing env vars: {string.Join(", ", missing)}"); return; }

When it happens

Trigger: Running the AutoGen.SemanticKernel sample's Create_Semantic_Kernel_Chat_Agent.RunAsync() in a process where OPENAI_API_KEY is null.

Common situations: Fresh repo clone; env var set at user scope but the sample launched from VS Code/WSL/Docker where it is not inherited; CI without secrets; typos in the variable name (e.g. OPENAI_APIKEY).

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/3908ad22fbe6b1bb. Report an issue: GitHub.