Short answer: Meta’s Sharing Debugger shows what Facebook’s crawler reads from your page and triggers a new scrape. Use it after you change a title, a description or an image, because Facebook keeps what it stored until it reads the page again. On LinkedIn, the Post Inspector shows what your page is missing and lets you request a re-scrape.
What the Sharing Debugger does
When someone shares a link on Facebook, Instagram or Messenger, Meta’s crawler, FacebookExternalHit, reads the page. It stores and shows the page’s title, description and thumbnail image.
Meta’s guide says the Sharing Debugger shows which meta tags the crawler scrapes, along with any errors or warnings. Each run also triggers a new scrape of your page. Meta’s best practices say the debugger helps when a page needs updating more often than the standard 24-hour update period allows.
Our Open Graph tags guide covers the tags themselves.
What Facebook’s crawler needs from your page
| Requirement | What Meta asks | What our pages answered |
|---|---|---|
| Compression | gzip and deflate encodings on your server | gzip on all four |
| Tags early in the page | Open Graph tags before the first 1 MB, or they’re cut off | Tags end before byte 3,100 |
| Speed | Content the crawler can fetch within a few seconds | 0.07 seconds or less, from our page cache |
| Range header | Answer with the bytes it asks for, or ignore the header | Header ignored, whole page sent |
| Access | Its user agent or IP addresses on your allow list | 200 to its user agent |
From Meta’s page on its web crawlers, read November 4, 2026; our pages measured the same day.
Meta adds that FacebookExternalHit might bypass robots.txt when it runs security or integrity checks. Our robots.txt guide explains that file, and our TTFB guide shows how to measure how fast your server answers.
How to refresh a link preview
A changed image needs a new address as well, since Meta keeps the cached copy for as long as the image URL stays the same. Meta also suggests running the URL through the Sharing Debugger whenever you update a page’s image, so the crawler fetches it before people share the page.
If your page was down when someone shared it, Meta says you can force a new crawl once it’s back, through the Sharing Debugger or the Sharing API. Our website down guide covers what to do during an outage.
On LinkedIn, the Post Inspector shows the data your page is missing, tells you when LinkedIn last updated its data and lets you request a re-scrape.
How to fix a link preview on Facebook
- Fix og:title, og:description, og:image, og:image:width and og:image:height on the page.
- If you changed the image, upload it under a new URL.
- Open Meta’s Sharing Debugger and paste the page’s address.
- Read the tags it found and any errors or warnings.
- Fix what it reports and run the address again, which makes the crawler read the page again.
- Run the same address through LinkedIn’s Post Inspector and request a re-scrape.
- Share the link again and check the new preview.
Our guide to creating a Facebook business page covers the page you’ll usually share from.
What Facebook’s crawler gets from our pages
On November 4, 2026 we requested four of our pages the way Meta’s crawler page says to simulate its crawler: compressed, with its user agent and a Range header. All four came from our page cache and answered 200, compressed with gzip, in 0.07 seconds or less.
Our Open Graph tags end within the first 3,100 bytes of each page, far inside the first 1 MB Meta reads. Our server ignores the Range header and sends the whole page, which Meta accepts.
The same day we moved the share images of 368 pages from WebP to JPEG, each under a new URL. Links shared before keep the old picture until Facebook reads those pages again, and the Sharing Debugger makes it do that on demand.
Before you share a link
- The page answers within a few seconds.
- Your server compresses pages with gzip or deflate.
- The Open Graph tags sit near the top of the page.
- Each replaced image went up under a fresh URL.
- The debugger’s last run listed no errors.
- LinkedIn’s Post Inspector has read the latest version.
RememberFacebook shows what its crawler stored, not what your page says now. After a change, run the page through the Sharing Debugger instead of waiting for the next update.
Link previews like these are part of our social media management service.
Quick answers about the Sharing Debugger
Why does my link preview show no image?
Meta’s crawler needs the page compressed, quick to load and with its Open Graph tags in the first 1 MB. Meta also asks for og:image:width and og:image:height, so the crawler can render the image right away instead of downloading and processing it first.
How often does Facebook refresh a link preview?
Meta’s best practices mention a standard 24-hour update period for the content it scrapes. If you need the change sooner, the Sharing Debugger refreshes what Meta scraped from your page when you run it.
Does the Sharing Debugger cover Instagram and Messenger links?
Meta’s FacebookExternalHit crawler reads links shared on Facebook, Instagram and Messenger. The Sharing Debugger shows how your page looks to that crawler, and each run makes the crawler read the page again.
Can robots.txt stop Facebook from showing my page?
Meta says you can block its crawlers with a disallow rule in robots.txt, but FacebookExternalHit might bypass it for security or integrity checks. A change can take up to 24 hours, because crawlers may cache robots.txt that long.
What does LinkedIn’s Post Inspector do?
It shows which data your page is missing for a better preview, tells you when LinkedIn last updated its data about the page and lets you request a re-scrape. It also explains how LinkedIn extracts your metadata.
Sources
Read on November 4, 2026. Meta for Developers: A Guide to Sharing for Webmasters, Meta Web Crawlers and Sharing best practices. LinkedIn: Post Inspector. Our case: four of our pages requested as Meta’s crawler, and our share-image change, on November 4, 2026.