wavetermdev/waveterm · error

dropping file with unsupported mimetype '%s' (OpenAI support

Error message

dropping file with unsupported mimetype '%s' (OpenAI supports images, PDFs, text/plain, and directories)

What it means

The OpenAI backend only supports file parts with mimetypes: images (image/*), application/pdf, text/plain, and 'directory' listings. Any other mimetype hits the default case and the part is rejected with this error listing the supported set. Unlike the others, this is an unsupported-feature error — the part must be converted or dropped by the caller.

Source

Thrown at pkg/aiusechat/openai/openai-convertmessage.go:393

		}, nil
	case part.MimeType == "directory":
		var jsonContent string

		if len(part.Data) > 0 {
			jsonContent = string(part.Data)
		} else {
			return nil, fmt.Errorf("directory listing part missing data")
		}

		formattedText := aiutil.FormatAttachedDirectoryListing(part.FileName, jsonContent)

		return &OpenAIMessageContent{
			Type: "input_text",
			Text: formattedText,
		}, nil

	default:
		return nil, fmt.Errorf("dropping file with unsupported mimetype '%s' (OpenAI supports images, PDFs, text/plain, and directories)", part.MimeType)
	}
}

// ConvertAIMessageToOpenAIChatMessage converts an AIMessage to OpenAIChatMessage
// These messages are ALWAYS role "user"
// Handles text parts, images, PDFs, and text/plain files
func ConvertAIMessageToOpenAIChatMessage(aiMsg uctypes.AIMessage) (*OpenAIChatMessage, error) {
	if err := aiMsg.Validate(); err != nil {
		return nil, fmt.Errorf("invalid AIMessage: %w", err)
	}

	var contentBlocks []OpenAIMessageContent
	imageCount := 0
	imageFailCount := 0

	for i, part := range aiMsg.Parts {
		switch part.Type {
		case uctypes.AIMessagePartTypeText:

View on GitHub (pinned to a4447c1563)

Solutions

1. Convert unsupported files to text/plain or a supported format before attaching (e.g. extract text from .docx/.csv)
2. Read the file and attach as text/plain content when it's fundamentally textual
3. Skip unsupported parts with a user-visible notice instead of failing the whole request
4. Check the mimetype against the supported list (image/*, application/pdf, text/plain, directory) before adding the part

Example fix

// before
part := uctypes.AIMessagePart{Type: "file", MimeType: "text/csv", Data: csvBytes} // unsupported
// after
part := uctypes.AIMessagePart{Type: "file", MimeType: "text/plain", FileName: "data.csv", Data: csvBytes} // send as plain text

var supportedPDFImage = func(mt string) bool {
    return strings.HasPrefix(mt, "image/") || mt == "application/pdf" ||
        mt == "text/plain" || mt == "directory"
}
// drop or convert parts where !supportedPDFImage(part.MimeType) before sending

func isOpenAISupportedFile(p uctypes.AIMessagePart) bool {
    if p.Type != uctypes.AIMessagePartTypeFile { return false }
    return strings.HasPrefix(p.MimeType, "image/") || p.MimeType == "application/pdf" ||
        p.MimeType == "text/plain" || p.MimeType == "directory"
}

When it happens

Trigger: Attaching files like .docx, .xlsx, .csv, application/json, image-less binaries, or audio/video parts to a message sent through the OpenAI backend; a generic file-attachment pipeline passing arbitrary mimetypes through unfiltered.

Common situations: Users attaching Office documents or spreadsheets in a chat UI; CSV/JSON data files attached as-is; feature parity gaps when switching backends (e.g. Anthropic accepts more types than this OpenAI path).

Related errors

• convertFileAIMessagePart expects 'file' type, got '%s'
• file part missing mimetype
• dropping PDF with URL (must be fetched and converted to base
• PDF file part missing data
• directory listing part missing data

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/bd58823bf33ae9b6. Report an issue: GitHub.