"To start seeing previews, please log on by opening the document"

ISSUE: Document preview for SharePoint 2013 search results randomly give an error "To start seeing previews, please log on by opening the document". CAUSE: The behavior occurs because the page that we use to show the preview (_layouts/15/wopiframe.aspx) is set up for anonymous access.  Since the user did not browse the site collections from where the documents to…

2