Still Having trouble?

If you've already changed readers in Firefox and the PDF's are still not rendering correctly, you may need to disable Firefox's native PDF viewer entirely as well.


This one is a bit more tricky and involves the use of about:config. Do the following:

  • Type in 'about:config' (without the quotes) in your address bar and press 'Enter' on your keyboard.
  • You will be prompted with a warning that says "This might void your warranty". Read the warning and click 'I'll be careful, I promise'.
  • Now type in "pdf" (without the quotes) in the search bar at the top:

  • Once you type "pdf", the results will be filtered to only show PDF-related results. Find 'pdfjs.disabled' and double left-click it so that it says 'true' for 'Value':

  • Done!

You can close the tab/window. Once you have set 'pdfjs.disabled' to 'true', Firefox's native PDF viewer has been disabled. There is no save button to hit - all changes are saved in real-time.