In my application the admin of the application can upload different favicon from time to time. Right now I am using the favicon on my page like this:
<link rel="shortcut icon" href="/img/favicon.ico?v=4f32ecc8f43d">
I have no issue updating the new favicon from my application.
The issue is that it doesn't get updated to end user unless he clears his cache (because it is a static file). To overcome this I have one solution in my mind: Update the favicon every time with new guid so that it can be updated at end machine on the next page load. The url for favicon will look like this then:
<link rel="shortcut icon" href="/img/c96e9689-e6af-4b36-839b-e2014f269f69.ico?v=4f32ecc8f43d">
This will solve the favicon refresh on end user's machine.
My concern is that on replacing the name of favicon from "favicon.ico" with .ico will impact SEO?