ERROR 404.3 Not Found for JSON file

This is because your IIS doesn’t have json MIME Type.

Open IIS Manager -> Mime types -> Add a new mime type like below

 

Extension: .json MIME Type: application/json

OR

Insert mimeMap like below in web.config.

<system.webServer>
  <staticContent>
    <mimeMap fileExtension=".json" mimeType="application/json" />
  </staticContent>
</system.webServer>