This article covers the 403 Forbidden error that prevents social media platforms from generating link previews for Finalsite pages, including how to confirm the WAF is blocking the crawler and when to contact Finalsite Support.
💡Quick answers
- What causes a 403 error on a social media link preview? Facebook, LinkedIn, and other platforms use automated crawlers to fetch page metadata when a link is shared. Finalsite's WAF can mistakenly identify these crawlers as suspicious traffic and block them.
- Which platforms are affected? Any platform that crawls URLs to generate link previews may be affected. Facebook and LinkedIn are the most commonly reported.
- How is this confirmed? Test the page URL in the Facebook Sharing Debugger. If it returns a 403, the WAF is blocking the crawler.
- Can this be fixed without contacting support? No. A WAF rule exception is required. Contact Finalsite Support if the debugger confirms a 403.
In this article
What causes this error
Social platforms like Facebook and LinkedIn send automated crawlers to fetch page metadata (title, description, and preview image) when a link is shared. Finalsite's WAF can mistake these crawlers for malicious bot traffic and return a 403 Forbidden error. When blocked, the link preview fails to generate or appears blank on the platform.
This is not a problem with the page itself. The page content and Composer configuration remain intact.
Diagnose a 403 on a social media link preview
Verify the page is publicly accessible
Before testing the crawler, confirm the page URL loads correctly in a browser without being signed in to Composer. If the page returns an error or requires authentication, that is a separate issue from the WAF block.
Test with the Facebook Sharing Debugger
Enter the page URL in the Facebook Sharing Debugger and run the test. This tool simulates how Facebook's crawler fetches the page and displays the full response, including any errors.
- If the debugger loads the page successfully, the issue may be intermittent or already resolved. Use the Scrape Again button to refresh the cached preview.
- If the debugger returns a 403, the WAF is blocking the crawler. Proceed to contacting Finalsite Support.
Contact Finalsite Support
If the Facebook Sharing Debugger confirms a 403 error, contact Finalsite Support. A WAF rule exception will need to be configured to allow social platform crawlers to access the page. Include the following in the ticket:
- Page URL. The full address of the page where the link preview is failing.
- Platforms affected. Which social networks are showing the blocked preview (for example, Facebook or LinkedIn).
- Debugger results. A screenshot or the shareable link from the Facebook Sharing Debugger showing the 403 response.
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