Why the wrong image appears

Tumblr uses the og:image tag for the link post card image. Wrong image usually means:

1. og:image points to the wrong URL
2. The link post was created when a different image was set (cached)
3. Multiple og:image tags – Tumblr picked one you didn’t intend
4. The image looks different at 540px dashboard width than at full size

Diagnosis steps

1. View page source and check the og:image value
2. Open the og:image URL directly in a browser
3. Search your HTML for duplicate og:image tags
4. Preview your image at 540px wide – text that’s legible at 1200px can become unreadable

Fixing it

Correct the og:image tag, then:

1. Delete the existing link post
2. Create a new link post with the same URL
3. Tumblr fetches fresh OG data

Remember that existing reblogs of the old post will keep the old image permanently.

Testing

curl -A "Tumblr/1.0" https://yoursite.com/page | grep -i "og:image"

Confirm there’s one og:image tag pointing to the correct absolute HTTPS URL.