microsoft/autogen · error · InvalidOperationException

Invalid Message as message from other.

Error message

Invalid Message as message from other.

What it means

Thrown from the legacy Message path (ProcessIncomingMessagesForOther/ProcessMessage) when a Message from another party has null/empty content and no FunctionName, so it can't be mapped to a ChatRequestUserMessage or ChatRequestToolMessage. The connector refuses to fabricate a user message from nothing.

Source

Thrown at dotnet/src/AutoGen.OpenAI.V1/Middleware/OpenAIChatRequestMessageConnector.cs:265

        {
            return [new ChatRequestSystemMessage(message.Content) { Name = message.From }];
        }
        else if (message.Content is string content && content is { Length: > 0 })
        {
            if (message.FunctionName is not null)
            {
                return new[] { new ChatRequestToolMessage(content, message.FunctionName) };
            }

            return [new ChatRequestUserMessage(message.Content) { Name = message.From }];
        }
        else if (message.FunctionName is string _)
        {
            return [new ChatRequestUserMessage("// Message type is not supported") { Name = message.From }];
        }
        else
        {
            throw new InvalidOperationException("Invalid Message as message from other.");
        }
    }

    private IEnumerable<ChatRequestMessage> ProcessTextMessage(IAgent agent, TextMessage message)
    {
        if (message.Role == Role.System)
        {
            return [new ChatRequestSystemMessage(message.Content) { Name = message.From }];
        }

        if (agent.Name == message.From)
        {
            return [new ChatRequestAssistantMessage(message.Content) { Name = agent.Name }];
        }
        else
        {
            return message.From switch
            {

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Filter out or skip empty legacy messages before sending the conversation to the agent
2. Give the message non-empty Content or a FunctionName so it maps to ChatRequestUserMessage/ChatRequestToolMessage
3. Migrate message production code to TextMessage so the legacy branch is never hit

Example fix

// before
messages.Add(new Message(Role.User, content: null, from: "User")); // throws

// after
messages.Add(new Message(Role.User, content: "(empty turn)", from: "User"));
// or better: new TextMessage(Role.User, "(empty turn)", from: "User")

if (msg is Message { Content: null or "" , FunctionName: null }) { /* skip or give placeholder content */ }

catch (InvalidOperationException ex) when (ex.Message == "Invalid Message as message from other.") { /* filter empty legacy messages from history */ }

When it happens

Trigger: A legacy Message with From != agent.Name, Content null or empty string, and FunctionName null, passed through ProcessIncomingMessages.

Common situations: Replaying old conversation logs that contain empty filler messages; upstream agent emitting an empty legacy Message on error; migration from the deprecated Message API.

Related errors

• Invalid Message as message from self.
• Please set AZURE_OPENAI_API_KEY environment variable.
• Please set AZURE_OPENAI_ENDPOINT environment variable.
• Please set environment variable AZURE_OPENAI_API_KEY
• Invalid return message type {message.GetType().Name}

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/67d15a4e9ebd5f81. Report an issue: GitHub.