How to disable the built-in PDF viewer in Mozilla Firefox and use another viewer

Based on original article found here:

If you'd rather not use the built-in PDF Viewer, you can use another PDF viewer like Adobe Reader, Nitro PDF Reader or Sumatra PDF.

To switch from the built-in PDF viewer to another PDF viewer:

  1. Click the menu button New Fx Menu and choose Options.

  2. Select the Applications panel.
  3. Find Portable Document Format (PDF) in the list and click on it to select it.
  4. Click on the drop-down arrow in the Action column for the above entry and select the PDF viewer you wish to use.


    Note: If you want to view PDF files in Firefox using a plugin, instead of in an external PDF reader application, select Use PDF reader name (in Firefox).
  5. Close the about:preferences page. Any changes you've made will automatically be saved.