Cause : This error is encountered when default page of your website is not set.
Resolution :
1. Add your default page name in your web.config file
<system.webServer>
<defaultDocument>
<files>
<add value="myDefault.aspx"/>
</files>
</defaultDocument>
</system.webServer>
2. Set default page from your hosting CP options available in knowledgebase section.
3. Set default page from IIS.
