Could not convert JDOM document into string... Root element not set
In some cases, viewing the XML content of a page will result in the following error message:
Could not convert JDOM document into string: Exception outputting Document: Root element not set
To resolve this, try changing the Template content from:
<system-region name="DEFAULT"/>
to:
<xml>
<system-region name="DEFAULT"/>
</xml>
This will ensure that the content within the DEFAULT region always has a root element.