Since recently upgrading Confluence to latest stable versions, pages with excerpt-include references to the page on which they are on no longer work correctly. Instead displaying the message...

Error rendering macro 'excerpt-include' : null

So, to clarify. Impacted pages have the "Excerpt Include" macro with the "Page Containing the Excerpt" parameter set to the current page, the very same page where the macro itself resides. Hope that makes sense.

Here's the source, looks like this could be an issue with the Macro Browser as the name parameter appears to be a null link. Hope this helps...

<ac:structured-macro ac:name="excerpt-include"><ac:parameter ac:name=""><ac:link /></ac:parameter></ac:structured-macro>