David Cuenca reports on mediawiki-l that a PDF from Google docs does not render on Commons. See http://thread.gmane.org/gmane.org.wikimedia.mediawiki/41507 for his message.
The PDF's URL is: https://commons.wikimedia.org/wiki/File:Interproject_links_tabbed_interface_proposal_presentation.pdf
Visiting a thumbnail's URL (https://upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Interproject_links_tabbed_interface_proposal_presentation.pdf/page1-800px-Interproject_links_tabbed_interface_proposal_presentation.pdf.jpg) reveals the following error message:
Error generating thumbnail
Error creating thumbnail: convert: no decode delegate for this image format `/tmp/magick-STzEaZl6' @ error/constitute.c/ReadImage/532.
convert: missing an image filename `/tmp/transform_d32a7a881ee9-1.jpg' @ error/convert.c/ConvertImageCommand/3011.
Version: unspecified
Severity: normal