Current Firefox versions have enabled a built-in PDF Viewer that doesn't have all features that other PDF readers like the Adobe Reader have or may not function properly otherwise.

You can change the action for Portable Document Format (PDF) from Preview in Firefox to use the Adobe Reader or set to Always Ask in "Firefox > Preferences > Applications".

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

See also:

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

Thanks for you quick response! Much appreciated.

I apologize. I guess I should have included that we're posting PDFs on our websites and are concerned that others who are accessing them are viewing the glitchy images. I'm assuming there's no fix for this problem at this time, but perhaps with future versions it will be rectified?

The good news is that when they're downloaded, they're fine.

Thanks again.

I am having the exact same issues. We upload larger pdf's frequently to send to our clients for approval and if they viewing the link through the new firefox pdf viewer they are seeing these issues (boxes where the drop shaddows should be). Most annoying!

I hope this gets fixed soon.

Cheers