This may well be a limitation of the JavaScript-based PDF Viewer. It currently does not support all the feature of the Adobe plugin (or stand-alone version of Adobe Reader). You can test that theory using the steps in this article: View PDF files in Firefox or choose another viewer.

While an end user can switch around among viewers by changing their Firefox options, unfortunately there currently is no way for websites to detect which viewer is in use and assist visitors in a personalized manner. I think for now you may need to recommend that Firefox users use the above article for assistance if more complex PDFs do not render as expected.

Thanks for your advice.

I tried by following the steps of the article "How to disable the built-in PDF viewer and use another viewer", but still does not work.

Any other suggestions?

Thanks.

Could you clarify what you mean by "still does not work" -- does the PDF still load in the native Firefox viewer, or does the form load in the Adobe plugin and the fields still are not populated? For the second problem, it's hard to know what might be happening there without hands-on access to a problem PDF.

By the way, there are some security updates for the Adobe Reader 10.1.x series, and corresponding browser plugin. Try using Help > Check for Updates from within Adobe Reader to install those. I think 10.1.7 is the latest in the series.

You can set the pdfjs.disabled pref to true on the about:config page to disable the build-in PDF viewer.

You can check the value of the plugin.disable_full_page_plugin_for_types pref on the about:config page and remove the application/pdf part if present or reset the pref to the default via the right-click context menu.

• http://kb.mozillazine.org/about:config

See also:

• https://support.mozilla.org/kb/view-pdf-files-firefox-without-downloading-them