IIS server blocking access to .webp files

The fastest solution with less headache is to just add the file extension .webp to the mime types as below:

1. Select website from IIS Manager:

2. Add file extension to Mime Types:

You'll need to add this config to your webconfig file:

<configuration> 
    <system.webServer> 
        <staticContent> 
            <mimeMap fileExtension=".webp" mimeType="image/webp" /> 
        </staticContent> 
    </system.webServer> 
</configuration>

Ok figured it out.

I had to allow the mime type in iis manager.

https://technet.microsoft.com/en-us/library/cc725608(v=ws.10).aspx