Work in progress: The team is figuring this out still.
Check out these folks who already have though!
Error rendering macro 'viewpdf'
com.atlassian.confluence.macro.MacroExecutionException: com.atlassian.confluence.macro.MacroExecutionException: The viewfile macro is unable to locate the attachment "AeroPac 2012 100k' Program Report.compressed.pdf" on this page
Error rendering macro 'viewpdf'
com.atlassian.confluence.macro.MacroExecutionException: com.atlassian.confluence.macro.MacroExecutionException: The viewfile macro is unable to locate the attachment "Qu8k - The Story - Final.pdf" on this page
SuperLokiReport.pdf