# Bad value “favicon” for attribute “type” on element “link”: Subtype missing. > Canonical HTML version: https://rocketvalidator.com/html-validation/bad-value-favicon-for-attribute-type-on-element-link-subtype-missing > Attribution: Rocket Validator (https://rocketvalidator.com) > License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) MIME types (also called media types) follow a strict `type/subtype` structure as defined by IETF standards. For example, `image/png` has the type `image` and the subtype `png`. The value `"favicon"` doesn't follow this format — it has no slash and no subtype — so the validator reports "Subtype missing." This is a common mistake that happens when developers confuse the purpose of the icon (a favicon) with the format of the file (an image in a specific encoding). While most browsers are forgiving and will still display the favicon even with an invalid `type` value, using incorrect MIME types can cause issues. Some browsers or tools may ignore the `` element entirely if the `type` doesn't match a recognized format. It also hurts standards compliance and makes your HTML less predictable across different environments. The correct MIME type depends on the file format of your favicon: - `.ico` files: `image/x-icon` (or `image/vnd.microsoft.icon`) - `.png` files: `image/png` - `.svg` files: `image/svg+xml` - `.gif` files: `image/gif` It's also worth noting that the `type` attribute on `` is entirely optional. If omitted, the browser will determine the file type from the server's `Content-Type` header or by inspecting the file itself. Removing it is a perfectly valid fix. ## Examples ### ❌ Invalid: using "favicon" as the type ```html ``` The value `"favicon"` is not a valid MIME type, triggering the validation error. ### ✅ Fixed: using the correct MIME type for a PNG favicon ```html ``` ### ✅ Fixed: using the correct MIME type for an ICO favicon ```html ``` ### ✅ Fixed: using the correct MIME type for an SVG favicon ```html ``` ### ✅ Fixed: omitting the type attribute entirely ```html ``` Since the `type` attribute is optional for ``, removing it avoids the error and lets the browser detect the format automatically. This is often the simplest and most maintainable approach.