Blocked crawler

Linespider is probably blocked by your robots.txt. It respects robots.txt, so a blanket Disallow: / kills previews.

Diagnosis checklist

1. Check robots.txt – is Linespider disallowed?
2. Check for all three required OG tags – LINE only reads og:title, og:description, and og:image. All three must be present.
3. Check server-side rendering – curl the URL and verify tags are in the response, not JavaScript-injected.
4. Check HTTP status – must return 200 OK.
5. Check HTTPS – valid certificate required.
6. Check LINE app settings – the user may have disabled link previews in the app.

Allowing Linespider in robots.txt

User-agent: Linespider
Allow: /

Place before any blanket disallow rules.

Remember: only 3 tags

LINE ignores everything except og:title, og:description, and og:image. Having og:url or og:type won’t help. Make sure those three are present.

Testing your fix

curl -A "Linespider/1.1" https://yoursite.com/page | grep -i "og:title\|og:description\|og:image"

All three tags visible? Share in a LINE chat to verify.