404: The file is located elsewhere
Open the output icon URL. Check spelling, upper case and subdirectories. icons/favicon.png is resolved relative to the document address; /icons/favicon.png Starts at the domain root. An HTML-base element can change relative paths.
HTTP 200, but HTML instead of an image file
Some systems provide their start page with status 200 for missing icons. This is not a usable icon. Check the server file type and routing rule. The HTML entry type="image/png" alone does not prove correct content.
Icon present, but Google does not show it
Check the reference on the homepage, the accessibility for Googlebot and Googlebot image, and a square motif. Google calls at least 8×8 pixels and recommends more than 48×48 pixels. A fixed icon URL and a clear motive help; the ad remains Google’s decision.
Google's Favicon Requirements
The iPhone lacks the Homescreen icon
A browser favicon does not automatically replace an explicit apple touch icon reference. Incorporate a matching PNG file and test the website again via “To the home screen”. An already stored symbol can still use the older representation.
Sizes does not fit the file
The attribute describes the existing size; it does not scale the image. The check shows the declaration, but does not read pixel measurements from the file. Open the graph and check the actual dimensions.
Only one standard path was found.
A file under /favicon.ico or /apple-touch-icon.png can be reached without being linked in HTML. Add an explicit matching reference so that the desired file is unique.