chenhg5/cc-connect · error

wecom-ws: file data is empty

Error message

wecom-ws: file data is empty

What it means

JSON parse failure on the response of POST /cgi-bin/message/send for an image message: the HTTP call itself succeeded but the body is not valid JSON matching the {errcode, errmsg} shape. Typically the endpoint returned an HTML error page (gateway/proxy issue), an auth redirect, or a truncated body instead of the expected API envelope.

Solutions

1. Load the file bytes into file.Data before calling SendFile (e.g. os.ReadFile into Data)
2. Check len(file.Data) at the call site and skip/queue empty attachments
3. Verify the upstream read/download that populated Data actually succeeded

Example fix

// before
file := core.FileAttachment{FileName: "report.pdf"} // Data empty
p.SendFile(ctx, rc, file)
// after
data, err := os.ReadFile("report.pdf")
if err != nil {
	return err
}
file := core.FileAttachment{FileName: "report.pdf", Data: data}
p.SendFile(ctx, rc, file)

if len(file.Data) == 0 {
	return fmt.Errorf("attachment %s has no data; load bytes before SendFile", file.FileName)
}

if err := p.SendFile(ctx, rc, file); err != nil && strings.Contains(err.Error(), "file data is empty") {
	log.Warn("empty attachment skipped", "name", file.FileName)
}

When it happens

Trigger: Called with core.FileAttachment{...} where Data is nil or an empty slice — e.g. a failed prior file read, or an attachment constructed with only FileName/Path but never loaded.

Common situations: Caller passed a path expecting the platform to read it (it does not — Data must be preloaded); the file was read with an error that was ignored; attachment produced from an empty download.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• wecom-ws: chatID is empty, cannot send file
• antigravity: invalid permission behavior
• app_id and app_secret are required
• app_id/app_secret are required
• attachment exceeds size limit ( MB)

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/4ffca0b45346e08c. Report an issue: GitHub.

Appendix: source

Thrown at platform/wecom/websocket_outbound_media.go:168

		return "image.gif"
	case "image/webp":
		return "image.webp"
	default:
		return "image.png"
	}
}

// SendFile uploads and sends a file through the WeCom AI Bot WebSocket API.
func (p *WSPlatform) SendFile(ctx context.Context, rctx any, file core.FileAttachment) error {
	rc, ok := rctx.(wsReplyContext)
	if !ok {
		return fmt.Errorf("wecom-ws: SendFile: invalid reply context type %T", rctx)
	}
	if rc.chatID == "" {
		return fmt.Errorf("wecom-ws: chatID is empty, cannot send file")
	}
	if len(file.Data) == 0 {
		return fmt.Errorf("wecom-ws: file data is empty")
	}

	mediaID, err := p.uploadWSMedia(ctx, "file", wsFileFileName(file), file.Data)
	if err != nil {
		return fmt.Errorf("wecom-ws: send file: %w", err)
	}
	if err := p.sendWSMediaMessage(ctx, rc.chatID, "file", mediaID); err != nil {
		return fmt.Errorf("wecom-ws: send file: %w", err)
	}
	return nil
}

func wsFileFileName(file core.FileAttachment) string {
	name := filepath.Base(strings.TrimSpace(file.FileName))
	if name != "" && name != "." {
		return name
	}
	switch strings.ToLower(file.MimeType) {

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