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I got a warning telling me Firefox no longer supports my operating system after updating to Firefox 16. I have Mac OS X 10.5.8 on a Macbook.


I have a Macbook, OS X 10.5.

After I updated my browser to Firefox 16, I got a warning, "Firefox no longer supports your operating system version and will be vulnerable to online attacks" which leads me to this page: http://support.mozilla.org/en-US/kb/firefox-no-longer-works-mac-os-x-10-5#os=mac&browser=fx16

On this page, it says BOTH Firefox 16 works and doesn't work with OS X 10.5, leaving me very confused. http://support.mozilla.org/en-US/kb/install-firefox-mac#os=mac&browser=fx16

I would like to have a secure version of Firefox without having to switch browsers or buy a new computer. Should I restore Firefox 15? Or is there something I should look out for?

Additional System Details

This happened

Not sure how often

This started when...

Today (Oct 13)

Installed Plug-ins

  • Shockwave Flash 10.3 r183
  • Version
  • Google Talk Plugin Video Accelerator version:
  • Microsoft Office for Mac SharePoint Browser Plug-in
  • DivX Plus Web Player version
  • DivX VOD Helper Plug-in
  • Facebook Video Calling by Skype
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in web pages. For more information, visit the QuickTime Web site.
  • The Flip4Mac WMV Plugin allows you to view Windows Media content using QuickTime.
  • Office Live Update v1.0
  • iPhoto6


  • User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.5; rv:16.0) Gecko/20100101 Firefox/16.0

More Information

  • Top 10 Contributor
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10751 solutions 96757 answers

Helpful Reply

Firefox 16 versions still work with your OS X 10.5 operating system, but that is the last version that will work.
Firefox 17 will require OS X 10.6 and later.

You can see the Firefox 17 (currently in beta) system requirements here:

Question owner

So there is no security compromise for using Firefox 16?

By the time Firefox 17 comes out I'll hopefully have a new computer. Just wanted to make sure that while I'm still using my macbook I still have the full browsing experience.

  • Top 10 Contributor
  • Moderator
10751 solutions 96757 answers

Helpful Reply

Firefox 16 fully works on your computer and there is no problem with the security in using Firefox 16. You can use that version without compromising anything.