Please update to Firefox 21, Update Firefox to the latest release then Reset Firefox Refresh Firefox - reset add-ons and settings

After getting the new version and refreshing my Firefox, I tried downloading a few PDF files. Nothing shows up in the "Library".

If you'd rather not use PDF Viewer, you can use a PDF reader plugin like Adobe Reader, Nitro PDF Reader or Sumatra PDF. To change from using the built-in PDF viewer to your PDF reader plugin, at 1st the top of the Firefox window, click on the Firefox button and then select Options then Select the Applications panel after that Find PDF in the list and click on it to select it. Then Click on the drop- down arrow in the Action column for the above entry and select Use PDF reader name .....

Hi ADeslandes9, I don't know whether the following is relevant, but just in case:

By default Firefox will keep history -- including download history -- for quite a long time, but it segregates downloads from regular windows and private windows into separate lists. If you are using a mix of regular and private windows, and open the Library dialog from a regular window, it will not show the downloads made in the private window, and vice versa. To see the private window list, with a private window active, press Ctrl+j to open about:downloads in a tab in that window.

More generally, downloads are now stored as a part of history. If you click over to the history section of the Library dialog and enter .PDF in the search box, do you see the files there? This display is less complete, of course, but if you don't have the history either, either your settings or an add-on are clearing it, or the Library is very broken.

You can check for problems with the places.sqlite database file in the Firefox profile folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file