Pdf viewer not see pdf file

[ctgraham]

The HTTP 204 response indicates that the system returned no content when the file was fetched. Check to ensure that this PDF actually exists in OJS and that it is found correctly in the files_dir.

See also:

OJS 2.4.8-1 (Current Stable Release) is missing PDF.JS PDF Viewer Plugin

Your PDF galley itself is missing or empty. Check your article galleys in the Editor interface and verify the file in the files_dir on the filesystem.