System.InvalidOperationException: Request format is unrecognized for URL unexpectedly ending in code example

Example: Request format is unrecognized for URL unexpectedly ending in '/grid'

<configuration>
  <system.web>
    <webServices>
      <protocols>
        <add name="HttpGet"/>
        <add name="HttpPost"/>
      </protocols>
    </webServices>
  </system.web>
</configuration>