Social Media Preview Debugging: Why Your Link Looks Wrong and How to Fix It
Common Causes of Broken Previews
Missing og:image tag. Image URL returns 404. Image file too small (< 200×200px). Meta tags inside a JavaScript-rendered component (not in server-rendered HTML). Cached old preview not yet refreshed. robots.txt blocking the crawler from accessing the page.
Platform-by-Platform Debugging
Facebook: use Sharing Debugger, click 'Scrape Again' to force refresh. LinkedIn: Post Inspector tool, re-inspect URL. Twitter: new link shares auto-scrape; old cached data expires after 7 days. Slack: unfurl.io for testing, or post link in a test channel and delete after.
Server-Side Rendering Requirement
All OG meta tags MUST be present in the HTML served to the crawler — not injected by client-side JavaScript after page load. Social scrapers do not execute JavaScript. Use server-side rendering or static generation for pages where social sharing matters.