Why it happens

Telegram tends to show nothing at all when it can’t build a complete preview. There is no partial fallback.

Diagnosis

1. Check for OG tags: confirm og:title, og:description, and og:image are in the page source. Without at least a title and image, Telegram may skip the preview entirely.
2. Verify server-side rendering: TelegramBot doesn’t run JavaScript. Check what it actually sees: bash curl -A "TelegramBot (like TwitterBot)" https://yoursite.com/page
3. Check robots.txt: make sure TelegramBot isn’t blocked: User-agent: TelegramBot Allow: /
4. Check for noindex: if your page has or ever had <meta name="robots" content="noindex">, Telegram may be suppressing the preview. Telegram remembers noindex even after removal, so use @WebpageBot to force a re-crawl.
5. Rule out VPN/proxy issues: try sharing from a device without a VPN.

Client-side rendering

If your OG tags only exist after JavaScript runs, TelegramBot sees nothing. Use server-side rendering, a pre-rendering service, or put static meta tags in your HTML shell before your JS framework takes over.

The noindex memory trap

A Telegram-specific gotcha: if TelegramBot ever crawled your page while noindex was present, Telegram remembers. Removing the directive isn’t enough. You must force a re-crawl through @WebpageBot to clear the cached suppression.

Testing your fix

Send your URL to @WebpageBot to force a fresh crawl, then share it in a chat to verify.