The og:image tag tells Facebook, WhatsApp, LinkedIn, Telegram, and iMessage which preview image to display when someone shares a link. When the image is broken (HTTP 404, 403, or invalid redirect), every share renders without a preview.
Why this matters
A WhatsApp share with a preview (large image + title + URL) earns roughly 5x more clicks than a plain text link. On LinkedIn the gap is even wider - posts with preview images get up to 7x the engagement. When og:image is broken, every share - organic from users, planned from your team - looks flat and forgettable.
Secondary impact: Facebook caches the broken state. Even after you fix the image, Facebook continues to show the old broken version for days until you manually refresh via the Sharing Debugger. People sharing your URL during that window get the bad render - lost opportunities you cannot reclaim.
Indirect SEO impact: social shares are signals Google considers (not directly, but they generate backlinks and traffic). Shares that get no clicks generate none of those signals.
How to detect
View source on a page, find og:image, and copy the URL. Open it directly in a browser. If it loads, fine. If you see 404, 403, or an error page, it is broken.
Complementary check: use Facebook Sharing Debugger (https://developers.facebook.com/tools/debug/). Paste the page URL and inspect what Facebook sees. The tool reports the og:image it parsed and whether it is reachable. Common error: "Provided og:image, https://...image.jpg, could not be downloaded due to status code 404".
Additional tools: LinkedIn Post Inspector (https://www.linkedin.com/post-inspector/), Twitter Card Validator (where still available). Both display the expected preview and surface errors.
How to fix
By cause:
Image deleted or moved (404): if the image is gone, re-upload to the same path or update the URL in the post editor > SEO box > Featured Image and pick a different one.
Image blocked (403): verify file permissions over FTP - they should be 644 (world-readable). Check .htaccess for hotlink protection or bot user-agent blocks. Facebook crawls with user-agent facebookexternalhit - confirm it is not blocked.
Mixed content (HTTPS page with HTTP image): ensure every og:image starts with https://. The Better Search Replace plugin can rewrite http:// to https:// across the database.
Relative path: some platforms do not resolve relative URLs. Use absolute URLs: https://example.com/wp-content/uploads/image.jpg, not /wp-content/uploads/image.jpg.
Wrong size: Facebook requires at least 200x200px and recommends 1200x630px. WhatsApp requires at least 300x200px. Compress with Smush or ShortPixel for the right balance of quality and weight.
After any fix, run the URL through Facebook Sharing Debugger and click "Scrape Again" to force Facebook's cache to refresh. Repeat in LinkedIn Post Inspector.
Common mistakes
First mistake: no fallback image. If a post has no Featured Image, no og:image - every share looks empty. Configure a default in your SEO plugin (Yoast: Search Appearance > General > Default image).
Second mistake: using WebP only. Facebook does not fully support WebP - some shares render with no image. Use JPG or PNG for og:image, even if the rest of the site uses WebP.
Third mistake: wrong aspect ratio. Facebook displays og:image at 1.91:1. A square (1:1) or portrait (4:5) image gets cropped. Design hero images at 1200x630.
Fourth mistake: skipping the Facebook cache refresh after fixing. Even after the source is corrected, Facebook continues showing the broken version for days. Always run the Sharing Debugger.
Verifying the fix
Run Facebook Sharing Debugger post-fix - the platform should display the new og:image. Share the URL in a private WhatsApp chat and verify the preview. After a week, check Google Analytics > Acquisition > Social for any uplift in social-referral traffic.