You shipped a new favicon. Your browser tab still shows the old one, Google shows a grey globe, and the icon on your phone's home screen is a blurry screenshot of your page. Favicons are tiny, but they fail in more places than almost any other asset, because several different systems fetch and cache them independently.

I build favicon.now, a favicon generator and checker, and most "it's broken" reports we see come down to the same handful of causes. This is the checklist I work through, roughly in order from most to least likely.

Part 1: The files themselves

1. Open every icon URL directly. Paste https://yoursite.com/favicon.ico , your PNG icons, your apple-touch-icon.png and your site.webmanifest into the address bar. Each should return HTTP 200 and the right content. A surprising number of "invisible" favicons are simply 404s, or a redirect to a login page.

2. Check the content type.…