To keep videos playing and PDF’s displaying, add-ons in Firefox occasionally have to be updated or ousted.
Firefox has add-ons that allow you to view content beyond simple web pages. There are two kinds of add-ons: plug-ins and extensions. Plug-ins are modules that run inside a frame on a web page, like embedded video content. Extensions go beyond just displaying content and add-on to the base functionality of Firefox. It gets a little blurry because some functionality can be implemented as either a plug-in or an extension, depending on the supported functionality and the preferences of the developer; PDF display add-ons in particular seem to show up in both formats.
Firefox has a great little tool for checking if your installed plug-ins are up to date:
- From Firefox, select “Add-ons” from the Tools menu (or just select the “Add-ons” menu if that’s all you see).
- On the list on the left, select “Plugins.”
- Click on the blue “Check to see if your plugins are up to date” link at the top of the list.
- Update everything that has been flagged as being out of date by clicking on the provided link. If there is more than one link, you will have to repeat the steps above after each update to get back to the links.
- There are almost always some plug-ins that Firefox won’t know about and will have a “Research” option. If it seems like these plug-ins might be handling content that you’re having trouble viewing, you should see if you can find newer versions by using the link or going to the developer’s website.
If you’re still having trouble viewing videos, try the suggestions at https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues#w_plugins.
There’s no tool for checking extensions, which may be where the problem is if you’re having trouble displaying PDF’s. There are often multiple PDF add-ons that may either all be out of date, or interfering with each other. In this case we suggest a little trial and error.
- As in step 1 above, bring up the “Add-ons” window.
- Select “Extensions” from the list at the left. Scan for anything mentioning PDF’s or Adobe and disable it.
- Select “Plugins” from the panel on the left, and look for anything mentioning PDF’s or Adobe, and select “Never Activate.”
- Now try to view a PDF. It should bring you to Adobe Reader or Preview. If this is acceptable to you, you’re all set.
- If you want to try to find a PDF viewer that will work inside Firefox, try enabling one PDF viewer at a time, testing with a PDF, and then disabling and trying another if it’s not satisfactory.
- If you can’t find a PDF viewer that works for you, go to adobe.com and download Adobe Reader–this will install a Firefox add-in that should be up to date. Be careful, though, with the install–it may try to sneak in some extra software; read carefully and uncheck any optional install choices.