letsencrypt .well-known acme-challenge (static file issue resolved when using ServiceStack)

web.config

<?xml version = "1.0" encoding="UTF-8"?>
 <configuration>
     <!-- PUT THIS FILE INSIDE THE .well-known directory to re-instate static file recognition -->
     <system.webServer>
         <staticContent>
             <mimeMap fileExtension = ".*" mimeType="text/json" />
         </staticContent>
        <handlers>
            <clear />
            <add name="StaticFile" path="*." verb="*" type="" modules="StaticFileModule,DefaultDocumentModule,DirectoryListingModule" scriptProcessor="" resourceType="Either" requireAccess="Read" allowPathInfo="false" preCondition="" responseBufferLimit="4194304" />
        </handlers>
     </system.webServer>
 </configuration>