Firefox 15.0.1 update ready, expect distribution soon

Martin Brinkmann
Sep 6, 2012
Updated • Sep 7, 2012

You may have read about the unfortunate bug in Mozilla Firefox 15 stable that is preventing the browser's private browsing mode from working correctly. The bug was discovered shortly after Firefox 15 was distributed to users of the stable channel of the browser, and Mozilla has been working diligently ever since to resolve the issue.

The private browsing mode bug affected all versions of the browser, from Firefox 15 to the latest Nightly builds. The defect caused the web browser to record data  to the browser's cache in private browsing mode even though that should not happen in first place. In fact, it is the opposite behavior of what the mode has been created for and problematic for Mozilla and users of the browser who thought that their actions would not be recorded.

It is a issue of trust for Mozilla mainly, which can easily be lost if sensitive features are not working like they should. For users the situation may have been even more precarious as it may have forced them to explain their browsing activities to third parties.

I mentioned yesterday that Mozilla was already testing release candidates of Firefox 15.0.1. which resolve the issue in the web browser. The update has now been moved to the official ftp server which is an indication that Mozilla is about to release the update to the public.

It is not clear if the update will be distributed later today, but it is very likely that all Firefox 15 users with automatic updates or update notifications enabled will receive notification of the new update in the coming 24 hour period. A changelog has not been posted yet, it is however likely that the private browsing mode bug fix is the only issue that Mozilla fixed in the release. I'll update the article if that is not the case.

The update is already listed on various download portals. If you are not using private browsing mode there is no need to rush to those sites to download the update early. If you depend on it, you may want to download the update immediately to have the issue fixed on your system.

The download will be made available on this page over at Mozilla.


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  1. Mon said on September 9, 2012 at 11:26 am

    @ Martin. I did not update it. I guess it was auto-update. I did check & find I already have the latest version & yet Firefox 15 was not overwritten by the new version. It;s not like that before.

    1. Martin Brinkmann said on September 9, 2012 at 11:32 am

      How do you know you have two versions of the browser installed then?

      1. Anonymous said on September 9, 2012 at 2:58 pm

        In the Programs & Features window. Both versions listed under its own Publisher / Installed On / Size / Version column. The first is Firefox 15, the second is Firefox 15.0.1. I only installed Firefox 7, update it manually up to 15, v.15.0.1 just appear automatically without removing v.15. I guess it’s somewhat like this “”?

      2. Martin Brinkmann said on September 9, 2012 at 3:26 pm

        What you can do is check the program files folder on your hard drive to see if there are two Mozilla Firefox entries listed here. If there are, try and load Firefox from here to see if they lead to 15.0 and 15.0.1. If that is the case, simply use the uninstaller in the Programs and Features control panel applet to remove Firefox 15.

        This should not be a issue as long as you do not check the option to remove your profile information as well. To be on the safe side, create a backup of your profile first using a program like MozBackup.

  2. Paul said on September 8, 2012 at 5:17 pm

    Interestingly when Firefox 15.0.1 installed it removed my Home Pages for a Firefox page and I had to recreate them.

  3. Maike said on September 7, 2012 at 5:49 pm

    The of PNG transparency continues. The PNG have a white background when u open it directly.

  4. ilev said on September 7, 2012 at 6:52 am
    1. Martin Brinkmann said on September 7, 2012 at 8:59 am

      Thanks for posting, the private browsing fix appears to be the only update in Firefox 15.0.1.

      1. Mon said on September 9, 2012 at 2:00 am

        Martin, I have now Firefox 15 & 15.0.1 in my laptop. I did not know how it happened, but would you say uninstall the other version[?].

      2. Martin Brinkmann said on September 9, 2012 at 10:13 am

        Have you installed the update manually and in another directory?

  5. Terence Kam said on September 7, 2012 at 5:02 am

    This is not the first time Mozilla screw up. Often they release a new version and then almost immediately follow it up with another update to fix a bug.

    Where’s their quality control? This is becoming a pattern of behavior for Mozilla!!

  6. Kaushal Shah said on September 6, 2012 at 10:59 pm

    Sure Joe, I will to update my firefox version. Let see then…

  7. joe said on September 6, 2012 at 10:46 pm

    Kaushal Shah upgrade to firefox 15.0.1

  8. Kaushal Shah said on September 6, 2012 at 10:23 pm

    I am using Firefox 12.0 whenever I get any issue report those to firefox they take so much time in solving them. The latest issue, i am facing is with plugin. There are some plugin which I have never install but they are in my firefox like Babylon and incredible toolbar. I don’t know from where they came.

    1. anony said on September 6, 2012 at 11:54 pm

      That toolbars is crapware from you not paying attention to softwares installation, which could be anything.

  9. mark said on September 6, 2012 at 6:03 pm

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