microsoft/autogen · error · InvalidOperationException

Invalid message type: {m.GetType().Name}

Error message

Invalid message type: {m.GetType().Name}

What it means

Thrown by ProcessIncomingMessages when strictMode is true and an incoming IMessage is not one of the supported types (TextMessage, ImageMessage, MultiModalMessage, ToolCallMessage, ToolCallResultMessage, AggregateMessage<ToolCallMessage,ToolCallResultMessage>, legacy Message, or ChatRequestMessage envelopes). In strict mode the connector must translate every message into Azure OpenAI ChatRequestMessage form; anything unrecognized aborts the batch.

Source

Thrown at dotnet/src/AutoGen.OpenAI.V1/Middleware/OpenAIChatRequestMessageConnector.cs:192

            if (m is IMessage<ChatRequestMessage> crm)
            {
                return [crm];
            }
            else
            {
                var chatRequestMessages = m switch
                {
                    TextMessage textMessage => ProcessTextMessage(agent, textMessage),
                    ImageMessage imageMessage when (imageMessage.From is null || imageMessage.From != agent.Name) => ProcessImageMessage(agent, imageMessage),
                    MultiModalMessage multiModalMessage when (multiModalMessage.From is null || multiModalMessage.From != agent.Name) => ProcessMultiModalMessage(agent, multiModalMessage),
                    ToolCallMessage toolCallMessage when (toolCallMessage.From is null || toolCallMessage.From == agent.Name) => ProcessToolCallMessage(agent, toolCallMessage),
                    ToolCallResultMessage toolCallResultMessage => ProcessToolCallResultMessage(toolCallResultMessage),
                    AggregateMessage<ToolCallMessage, ToolCallResultMessage> aggregateMessage => ProcessFunctionCallMiddlewareMessage(agent, aggregateMessage),
#pragma warning disable CS0618 // deprecated
                    Message msg => ProcessMessage(agent, msg),
#pragma warning restore CS0618 // deprecated
                    _ when strictMode is false => [],
                    _ => throw new InvalidOperationException($"Invalid message type: {m.GetType().Name}"),
                };

                if (chatRequestMessages.Any())
                {
                    return chatRequestMessages.Select(cm => MessageEnvelope.Create(cm, m.From));
                }
                else
                {
                    return [m];
                }
            }
        });
    }

    [Obsolete("This method is deprecated, please use ProcessIncomingMessages(IAgent agent, IEnumerable<IMessage> messages) instead.")]
    private IEnumerable<ChatRequestMessage> ProcessIncomingMessagesForSelf(Message message)
    {
        if (message.Role == Role.System)

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Construct the connector with strictMode: false so unsupported messages are forwarded unchanged
2. Convert foreign messages to TextMessage/MessageEnvelope<ChatRequestMessage> before they reach this agent
3. If the message is from another agent, ensure it is an aggregate or tool-call/result type the connector understands
4. Log m.GetType().Name at the call site to identify the offending producer

Example fix

// before
var connector = new OpenAIChatRequestMessageConnector(strictMode: true);
await agent.SendAsync(new MessageEnvelope<MyPayload>(new MyPayload())); // throws

// after
var connector = new OpenAIChatRequestMessageConnector(); // lenient passthrough
// or wrap the payload: new TextMessage(Role.User, Serialize(myPayload))

var supported = msg is TextMessage or ImageMessage or MultiModalMessage or ToolCallMessage or ToolCallResultMessage or AggregateMessage<ToolCallMessage, ToolCallResultMessage> or IMessage<ChatRequestMessage>;
if (!supported && strictMode) { /* convert to TextMessage first */ }

static bool IsSupportedByV1Connector(IMessage m) => m is TextMessage or ImageMessage or MultiModalMessage or ToolCallMessage or ToolCallResultMessage or AggregateMessage<ToolCallMessage, ToolCallResultMessage> or IMessage<ChatRequestMessage>;

catch (InvalidOperationException ex) when (ex.Message.StartsWith("Invalid message type")) { /* convert or drop the offending message */ }

When it happens

Trigger: Sending a message type like MessageEnvelope<someCustomPayload>, Microsoft.AutoGen messages, or another provider's message class into an agent pipeline containing this connector built with strictMode: true.

Common situations: Heterogeneous group chats where agents from different AutoGen packages share one conversation; custom user-defined IMessage implementations; strict-mode enabled to catch message-flow bugs but foreign messages legitimately flow through.

Related errors

• Invalid return message type {message.GetType().Name}
• Invalid return message type {message.GetType().Name}
• Invalid ChatResponseMessage
• Invalid streaming message type {reply.GetType().Name}
• No user message found.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/5c2c02a9c8f7fc07. Report an issue: GitHub.