microsoft/autogen · error · NotSupportedException

Role {textMessage.Role} is not supported

Error message

Role {textMessage.Role} is not supported

What it means

Error "Role {textMessage.Role} is not supported" thrown in microsoft/autogen.

Source

Thrown at dotnet/src/AutoGen.Anthropic/Middleware/AnthropicMessageConnector.cs:175

        {
            if (textMessage.Role == Role.User)
            {
                messages = new ChatMessage(
                    "user", textMessage.Content);
            }
            else if (textMessage.Role == Role.Assistant)
            {
                messages = new ChatMessage(
                    "assistant", textMessage.Content);
            }
            else if (textMessage.Role == Role.System)
            {
                messages = new ChatMessage(
                    "system", textMessage.Content);
            }
            else
            {
                throw new NotSupportedException($"Role {textMessage.Role} is not supported");
            }
        }
        else
        {
            // if from is not null, then the message is from user
            messages = new ChatMessage(
                "user", textMessage.Content);
        }

        return [new MessageEnvelope<ChatMessage>(messages, from: textMessage.From)];
    }

    private async Task<IEnumerable<IMessage>> ProcessMultiModalMessageAsync(MultiModalMessage multiModalMessage, IAgent agent)
    {
        var content = new List<ContentBase>();
        foreach (var message in multiModalMessage.Content)
        {
            switch (message)

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Use only user/assistant roles; convert system messages to system parameter

Example fix

Map Role.System to the system prompt and drop other unsupported roles

When it happens

Trigger: Thrown at dotnet/src/AutoGen.Anthropic/Middleware/AnthropicMessageConnector.cs:175 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/b44428d394204700. Report an issue: GitHub.