title: IIS Express - HTTP Error 500.19 0x800700b7 on 'mimeMap' for 'fileExtension' set to '.svg'
body: <p>I was adding the ability to serve SVG &amp; WOFF files to my Azure hosted web application. I found the following instructions:</p>
  <p><a href="https://blogs.iis.net/richma/archive/2014/01/07/adding-mime-types-to-your-windows-azure-web-site.aspx" rel="noreferrer">https://blogs.iis.net/richma/archive/2014/01/07/adding-mime-types-to-your-windows-azure-web-site.aspx</a></p>
  <p>Which I have followed by adding the below text to my Web.config file:</p>
  <pre><code>&lt;staticContent&gt;
      &lt;mimeMap fileExtension=&quot;.json&quot; mimeType=&quot;application/json&quot; /&gt;
      &lt;mimeMap fileExtension=&quot;.svg&quot; mimeType=&quot;image/svg+xml&quot; /&gt;
      &lt;mimeMap fileExtension=&quot;.woff&quot; mimeType=&quot;application/x-font-woff&quot; /&gt;
  &lt;/staticContent&gt;
  </code></pre>
  <p>This works when published to Azure. However, now I get the following error from IIS-Express whenever I attempt to <strong>start up the website in Debug mode locally</strong> for every resource the website attempts to serve.</p>
  <blockquote>
  <h3>HTTP Error 500.19 - Internal Server Error</h3>
  <p>The requested page cannot be accessed because the related configuration data for the page is invalid.</p>
  <h3>Detailed Error Information:</h3>
  <ul>
  <li>Module:           CustomErrorModule</li>
  <li>Notification     SendResponse</li>
  <li>Handler          StaticFile</li>
  <li>Error Code       0x800700b7</li>
  <li>Config Error     Cannot add duplicate collection entry of type 'mimeMap' with unique key  attribute 'fileExtension' set to '.svg'</li>
  <li>Config File      <em>snip</em>\web.config</li>
  <li>Requested URL    http://<em>snip</em>:14466/resources/img/<em>snip</em>.png</li>
  <li>Physical Path    C:*snip*\Resources\img*snip*.png</li>
  <li>Logon Method     Anonymous</li>
  <li>Logon User       Anonymous</li>
  </ul>
  <h3>Config Source:</h3>
  <pre><code>   58: &lt;mimeMap fileExtension=&quot;.json&quot; mimeType=&quot;application/json&quot; /&gt;
     59: &lt;mimeMap fileExtension=&quot;.svg&quot; mimeType=&quot;image/svg+xml&quot; /&gt;
     60: &lt;mimeMap fileExtension=&quot;.woff&quot; mimeType=&quot;application/x-font-woff&quot;/&gt;
  </code></pre>
  </blockquote>
  <p>It clearly hates my mimeMap for .svg but this works fine out in Azure Websites. Is there something I am missing for locally running these changes to the Web.config?</p>