Because computers don't fix themselves

Fillable forms in Adobe Reader / Firefox


Pre-filled and fillable forms don’t work properly in Firefox.


Apparently, Firefox added a built-in PDF viewer to their browser with release 19. Most people don’t notice the difference, as long as the pdf displays properly when you try to view it in the browser. However, if you are using a system that is supposed to pre-fill the form with data from the server, or you wish to make changes to fillable forms on the pdf document, those features are disabled in their default built-in viewer.


You can manually force Firefox to NOT use its built-in viewer, and go back to using Adobe’s PDF Viewer plug-in.

Step 1: Turn off the built-in viewer.

  • Type about:config in the address bar of Firefox, and hit enter.
  • Say yes to understanding that you can break Firefox.
  • Search for pdfjs.
  • Double click on pdfjs.disabled to change it from False to True.
  • Step 2: Re-enable Adobe in Firefox

  • In Firefox, go to Tools / Options
  • Click on the Applications Tab
  • Change all instances of Adobe Acrobat document to “Use Adobe Acrobat in Firefox”
  • Instances can be labelled:
  • Adobe Acrobat Forms Document
    Adobe Acrobat XML Data Package File
    Portable Document File

  • Click ok.