When you paste a link into WhatsApp, a small bot visits the page, reads a few tags in its code and builds the preview card: a title, a line of text and a picture. If any step fails, the card arrives without a picture, and the link looks less trustworthy than it is.

We hit every one of the causes below on our own sites in October 2026, measured each one, and fixed it. They are listed in the order we would check them.

1. robots.txt blocks the preview bot

Many sites close themselves to search engines while they are being built, with a robots.txt that says “disallow everything”. WhatsApp and Facebook use the same Meta preview bot, and it obeys robots.txt. On 11 of our sites the page and its image tags were correct, and the picture still never appeared, for exactly this reason.

  • Add /robots.txt to the end of your site’s address, for example sasateguh.com/robots.txt. If it says “User-agent: *” and “Disallow: /”, the preview bot is blocked too.
  • The fix is to allow the preview bots by name (facebookexternalhit, Facebot, WhatsApp) while keeping search engines out until launch.

2. The og:image tag is missing or broken

The picture comes from a tag called “og:image” in the page’s code. It must be a full address starting with https:// that opens the image directly, without a login. A small mistake is enough to break it: in one release of our own site the address was written twice, “https://sasateguh.comhttps://…”, and every case study page pointed WhatsApp at an image that did not exist. We now check this tag on every page before each release.

3. The image is too large

WhatsApp shows no picture when the preview image is too heavy. Its limit is about 300 KB. Two of our preview cards were PNG files of 410 KB and 1 to 1.3 MB, and showed no picture. We now save every preview card as a JPEG; measured on 20 October, they weigh 36 to 147 KB. A size of 1200 × 630 pixels is a safe shape for most apps.

4. WhatsApp is showing an old preview

WhatsApp and Facebook remember the preview of a link, including a preview without a picture. After fixing the cause, test with a link they have not seen before, for example by adding “?a=1” to the end, or ask Facebook to read the page again with its Sharing Debugger (“Scrape Again”).

A quick check you can do now

  • robots.txt does not block facebookexternalhit or WhatsApp.
  • The page has an og:image tag with a full https:// address that opens the picture.
  • The picture is a JPEG under 300 KB, about 1200 × 630 pixels.
  • You tested with a fresh link.