Q&A plugin search returning an error

When I use the search functionality of the Q&A plugin, I ge the following error:

Warning: Illegal offset type in isset or empty in /home/content/96/6926896/html/wp-includes/post.php on line 811

and it does not take to to a page with any of the questions listed, but rather the normal archive page.

Any idea what might be going on here? Thanks!