I noticed some time ago that three Mastodon features had stopped working on my blog. Each of them seemed like a separate problem, but they had the same root cause. In this blog post, I want to describe these issues and the simple fix.

Domain verification

Mastodon allows you to prove that you own a domain. The mechanism requires two steps:

Add a <link rel="me"> tag in your pages, pointing to your Mastodon profile

Add your website URL to your Mastodon profile

When Mastodon crawls your page and finds the backlink, it displays a green checkmark next to your URL in your profile.

I had set this up long ago and made it work, for my blog and GitHub. Then, the blog link stopped working, while GitHub's still worked. It made me sad, but I couldn't understand what changed.

Post preview

When you share a link on Mastodon, your instance crawls the page to generate a preview card. It reads the page's OpenGraph tags: title, description, and image.

My blog had all the correct tags.…