Reference the following examples:
DjVu files are not thumbnailing.
For file space, the description page is displaying but the image is replaced with a gray box and the words: "Error creating thumbnail: Unable to fetch XML for DjVu file". A similar result is obtained when the djvu is called inline as a
There is know documentation for this issue.
Use of DjVus on all Wikisources via InstantCommons is standard and does not exhibit this problem.
This issue has not been tested yet with pdfs or paged tiffs.