404 Error on site.webmanifest with IIS

The .webmanifest is a simple JSON file that tells the browser about your web application and how it should behave when ‘installed’ on the user’s mobile device or desktop, such as when the user adds the website to their iPhone or Android home screen.

A typical manifest file includes information about the app name, icons it should use, the start_url it should start at when launched, and more. It is often used by favicon generators for websites.

{
    "name": "",
    "short_name": "",
    "icons": [
        {
            "src": "/android-chrome-192x192.png",
            "sizes": "192x192",
            "type": "image/png"
        },
        {
            "src": "/android-chrome-256x256.png",
            "sizes": "256x256",
            "type": "image/png"
        }
    ],
    "theme_color": "#000000",
    "background_color": "#000000",
    "display": "standalone"
}

The fix to make IIS return this file correctly, is to add the below 2 lines just before the closing </staticContent>:

<remove fileExtension=".webmanifest" />
<mimeMap fileExtension=".webmanifest" mimeType="application/json" />