In my personal experience, I have found that using a favicon file with the extension .ico tends to work better than using a png file. It is also important to use the full domain name when linking to your favicon, rather than relying on relative links. If you encounter issues loading your favicon in the browser and simply refreshing the page does not solve the problem, try clearing your browser's cache before attempting to view the favicon again.
The following 3 favicon links have been tested and confirmed to work on various browsers and devices:
When implementing favicon code, it should resemble something like this:
<link rel="icon" href="http://www.domain.com/content/images/icons/favicon.ico" type="image/x-icon" />
<link rel="shortcut icon" href="http://www.domain.com/content/images/icons/favicon.ico" />
<link rel="apple-touch-icon" href="http://www.domain.com/content/images/icons/favicon.ico">
If you prefer to keep your links as relative paths without the .ico extension, consider the following code snippet:
<link rel="icon" href="/content/images/icons/tick-circle.png" type="image/x-icon" />
<link rel="shortcut icon" href="/content/images/icons/tick-circle.png" />
<link rel="apple-touch-icon" href="/content/images/icons/tick-circle.png">