Sorry to hear about this problem.

You mentioned that changing the setting for "Portable Document Format (PDF)" doesn't help. What have you tried, for example, does "Always Ask" cause Firefox to prompt you to open/save the PDF? In other words, is the problem only with the plugin-in-a-tab scenario, or is the setting being ignored?

If the problem is only in a tab, could you start by checking this preference:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste full and pause while the list is filtered

(3) If the plugin.disable_full_page_plugin_for_types preference includes application/pdf you can either double-click it and edit that out (you might need to remove an extra comma to clean up the list after editing) or right-click > Reset the preference.

If you changed that, does it help?

If the PDF setting has stopped working, there could be some settings confusion in one of Firefox's settings files. Unfortunately, the file is very hard to edit, so we generally suggest renaming it and letting Firefox generate a new one. After doing that, you will need to switch from the PDF Viewer back to Adobe. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename mimeTypes.rdf to something like mimeTypes.old.

Start Firefox back up again and it should extract default application settings from the registry. Then you can switch your viewer (View PDF files in Firefox or choose another viewer). Does this help at all?

Thank you for your response.

I have tried changing the application defaults to every option including manually browsing for my Adobe .exe file.

When I have it set to Ask, the file will go through the loading motions but it's a blank screen.

When I set it to Use Adobe Default, it opens a blank screen but doesn't seem to do anything to try and open the document.

I have tried uninstalling and re-installing - didn't work. I tried deleting the value in plugin.disable_full_page_plugin_for_types I tried renaming the mimeTypes file Nothing seems to work.

The previous version was working fine, is there a way to undo the update?

I tried one last thing and looks like it's working now YAY. I disabled all my add-ons and it worked. I then went back and enabled them again and still working. Hopefully it continues to work :)