iawia002/lux · error

can't match gif content downloadable url

Error message

can't match gif content downloadable url

What it means

In the Reddit extractor's GIF branch: the page matched 'preview\.redd\.it/.*gif', so it captures the full 'https://preview.redd.it/...gif?format=mp4...' URL from the HTML. If that capture comes back empty, extraction fails. Like the mp4 branch, the guard indexes [0] directly — a nil MatchOneOf panics before this check, so the error only fires for an empty-string capture.

Source

Thrown at extractors/reddit/reddit.go:141

				Streams: map[string]*extractors.Stream{
					"default": {
						Parts: []*extractors.Part{
							{
								URL:  imgURL,
								Size: size,
								Ext:  "jpg",
							},
						},
						Size: size,
					},
				},
				URL: url,
			},
		}, nil
	} else if utils.MatchOneOf(html, `https:\/\/preview\.redd\.it\/.*gif`) != nil {
		gifURL := utils.MatchOneOf(html, `https:\/\/preview\.redd\.it\/.*?\.gif\?format=mp4.*?"`)[0]
		if gifURL == "" {
			return nil, errors.New("can't match gif content downloadable url")
		}

		gifURL = strings.ReplaceAll(gifURL, "&", "&")
		gifURL = strings.ReplaceAll(gifURL, "\"", "")

		size, err := request.Size(gifURL, "reddit.com")
		if err != nil {
			return nil, errors.New("can't get video size")
		}

		streams := map[string]*extractors.Stream{
			"default": {
				Parts: []*extractors.Part{
					{
						URL:  gifURL,
						Size: size,
						Ext:  "mp4",
					},

View on GitHub (pinned to dd00f6d258)

Solutions

1. Fetch the post HTML and search for 'preview.redd.it' to see the actual URL format now served
2. Update the gif capture regex in extractors/reddit/reddit.go to match the current preview URL shape
3. Nil-guard the MatchOneOf result before indexing [0] so markup changes produce this error instead of a panic
4. Retry once — Reddit serves different markup variants across requests

Example fix

// before
gifURL := utils.MatchOneOf(html, `https:\/\/preview\.redd\.it\/.*?\.gif\?format=mp4.*?"`)[0]
if gifURL == "" {
    return nil, errors.New("can't match gif content downloadable url")
}

// after
gifMatch := utils.MatchOneOf(html, `https:\/\/preview\.redd\.it\/.*?\.gif\?format=mp4.*?"`)
if gifMatch == nil || gifMatch[0] == "" {
    return nil, errors.New("can't match gif content downloadable url")
}
gifURL := gifMatch[0]

defer func() {
    if r := recover(); r != nil {
        err = fmt.Errorf("reddit extractor panicked (gif branch markup change): %v", r)
    }
}()
_, err = reddit.Extract(url, opts)
if err != nil && strings.Contains(err.Error(), "can't match gif content") {
    // preview.redd.it URL shape changed: skip and report
}

When it happens

Trigger: Reddit changed the preview URL shape for gif posts (different host like v.redd.it or i.redd.it, dropped '?format=mp4', changed query ordering) so `https:\/\/preview\.redd\.it\/.*?\.gif\?format=mp4.*?"` no longer captures content.

Common situations: Site markup drift on Reddit's preview CDN links; posts converted from gif to native video between the og:video check and the gif branch; HTML-escaped URLs (&) altering the match.

Related errors

• can't match mp4 content downloadable url
• ErrURLParseFailed
• Could not read page data
• this page has no playlist
• could not find video in page

AI-assisted analysis of iawia002/lux@dd00f6d258 (2026-08-15). Data as JSON: /api/errors/168677cc2e9198e4. Report an issue: GitHub.