You will have to add the .pdf file extension yourself is Firefox leave this file extension blank to make Windows recognize the file as a PDF file.

Try rename/remove the handlers.json and remove the previously used mimeTypes.rdf file in the Firefox profile folder to reset all file actions.

• http://kb.mozillazine.org/mimeTypes.rdf
• http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thank you for the response, I did remove the previous mimeTypes.rdf and handlers.json yesterday, which did reset all the actions in Applications.

Is there a way to edit either of those to have Firefox automatically append the ".pdf" suffix to the file when saving? The site in particular has a list of documents we are downloading and combining into one document for later viewing. I was attempting to find a "one click" solution to download, rather than having to open in the PDF previewer or Acrobat and "Saving as..." or having to rename each individual file after saving.

If this still happens with a freshly created handlers.json file then it is more likely a problem with related Windows Registry keys (HKCR\.pdf or a linked MIME database key).

• HKEY_CLASSES_ROOT\.pdf
• HKEY_CLASSES_ROOT\MIME\Database\Content Type\