What causes "failed to create request" in xpzouying/xiaohongshu-mcp?

Print/log the offending imageURL from the wrapped error and inspect for control characters or bad escapes.

failed to create request

Error message

failed to create request

What it means

DownloadImage wraps an http.NewRequest failure (pkg/downloader/images.go:50). Although isValidImageURL already rejects malformed URLs, http.NewRequest still parses the URL itself and can fail on control characters, invalid percent-escapes, or unsupported schemes that slipped past the prefix check. This is a client-side URL construction error — no network I/O has happened.

Source

Thrown at pkg/downloader/images.go:50

		savePath: savePath,
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
	}
}

// DownloadImage 下载图片
// 返回本地文件路径
func (d *ImageDownloader) DownloadImage(imageURL string) (string, error) {
	// 验证URL格式
	if !d.isValidImageURL(imageURL) {
		return "", errors.New("invalid image URL format")
	}

	// 创建请求并设置请求头
	req, err := http.NewRequest("GET", imageURL, nil)
	if err != nil {
		return "", errors.Wrap(err, "failed to create request")
	}

	// 设置 User-Agent，模拟浏览器请求
	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36")

	// 设置 Referer，使用图片 URL 的域名
	parsedURL, _ := url.Parse(imageURL)
	if parsedURL != nil {
		req.Header.Set("Referer", fmt.Sprintf("%s://%s/", parsedURL.Scheme, parsedURL.Host))
	}

	// 下载图片数据
	resp, err := d.httpClient.Do(req)
	if err != nil {
		return "", errors.Wrapf(err, "failed to download image from %s", imageURL)
	}
	defer resp.Body.Close()

View on GitHub (pinned to 332d196854)

Solutions

Print/log the offending imageURL from the wrapped error and inspect for control characters or bad escapes.
Trim whitespace and re-encode: url.Parse + u.String(), or strings.TrimSpace before calling.
Validate with net/url.Parse yourself before invoking the downloader.
Sanitize at ingestion time so bad URLs never reach DownloadImages batches.

Example fix

// before
path, err := downloader.DownloadImage(rawURL)
// after
cleaned := strings.TrimSpace(rawURL)
if _, err := url.Parse(cleaned); err != nil {
    return fmt.Errorf("skip bad url %q: %w", cleaned, err)
}
path, err := downloader.DownloadImage(cleaned)

Defensive patterns

Strategy: validation

Validate before calling

u, err := url.Parse(strings.TrimSpace(rawURL))
if err != nil || u.Scheme == "" || u.Host == "" {
    return fmt.Errorf("invalid image url %q", rawURL)
}

Try / catch

path, err := dl.DownloadImage(imgURL)
if err != nil && strings.Contains(err.Error(), "failed to create request") {
    log.Printf("malformed url %q: %v", imgURL, err)
    return nil // skip bad URL in batch
}

Prevention

Trim and re-encode scraped URLs (strip control chars/newlines).
Validate with url.Parse before downloading.
Sanitize URL sources at ingestion, not download time.
In batches, skip-and-log invalid URLs rather than aborting.

When it happens

Trigger: Calling DownloadImage(url) or DownloadImages with a URL containing raw control characters (newline/tab from copied log lines), invalid percent-encoding like %zz, or a scheme http.NewRequest rejects, after passing the http(s)-prefix check.

Common situations: Image URLs scraped from HTML carrying embedded newlines or whitespace; unescaped characters from upstream data feeds; hand-built URLs with bad query encodings.

Understand the failure class

Background: "Invalid URL" / "URL cannot be empty": fix the malformed or missing URL behind request-construction failures — this error's family across 50 libraries.

Related errors

AI-assisted analysis of xpzouying/xiaohongshu-mcp@332d196854 (2026-09-05). Data as JSON: /api/errors/dd3baf9bfd26da97. Report an issue: GitHub.