Early Problems With Flash Player Protected Mode In Firefox 13

Yesterday Adobe released Flash Player 11.3 which included a new Protected Mode for Firefox – this is a new security enhancement designed to limit the impact of attacks launched from malicious SWF (Flash) files against Adobe Flash Player when running in Firefox 4.0+

It applies only to Windows Vista and Windows 7 – so XP and Mac users can ignore this article (any Flash issues you have can’t be related to Protected Mode). Updated 27th July – see updates at bottom of this article.

Protected Mode Issues – Whilst it is a welcome security improvement, early reports are coming in from some Vista and W7 users that it may cause problems with Flash content – it either crashes Firefox 13 or fails to display Flash content correctly. Adobe have released a (hopefully) temporary workaround for this issue which involves disabling Protected Mode.

Only apply this workaround if you have problems with Flash Player since upgrading to version 11.3 (and are using Firefox on Vista/W7).

To Disable Protected ModeClose Firefox. You now need to edit an Adobe configuration file called mms.cfg which is located in the following folder:

Windows 32bit – C:\windows\system32\macromed\flash OR
Windows 64bit – C:\windows\syswow64\macromed\flash

Tip: to edit this file, when you double click it you may need to choose ‘Select a program from a list of installed programs’ then select ‘Notepad’ then press OK to open the file in the Notepad text editor.

Add the following line then save the file and close it: ProtectedMode = 0 (The value is a zero, not the letter o). If you do not have a mms.cfg file in the relevant folder, create a new blank text file using Notepad, type in the line above and then save it as a file called mms.cfg in the relevant folder.

Hopefully this will cure the Flash Player issues until Adobe (or Mozilla) can release an update to fix the problem. Once they have released an update/fix you should re-enable Protected Mode for best security.

To Enable Protected Mode – Close Firefox and edit the mms.cfg file again – delete the line you added earlier then save the file and close it.

Other Steps – The problem may also be caused by conflicting add-ons. Mozilla have published a couple of solutions here which include disabling the faulty RealPlayer Browser Record add-on.

UPDATED 17th June 2012 – Firefox 13.0.1 has now been released with the following fixes:

– Flash 11.3 sometimes caused a crash on quit
– Windows Messenger did not load in Hotmail, and the Hotmail inbox did not auto-update
– Hebrew text sometimes rendered incorrectly

The Flash fix may help users who experienced Protected Mode crashes when closing Firefox (though it may not fix crashes during playback of Flash content). Get the latest update from Menu bar \ Help \ About Firefox.

UPDATED 27th July 2012 – Adobe have released yet another updated version of Flash Player (11.3.300.268) for all web browsers to (hopefully) resolve these problems.

13 Responses to: "Early Problems With Flash Player Protected Mode In Firefox 13"

  1. fullmetal says:

    It didn’t work for me, tried rebooting and all.

    • Joe90 says:

      if you have 11.3 and FF13 and this didn’t fix it then it’s not protected mode causing your problem

      11.3 had a lot of other changes – another fix could be to upgrade your graphics card drivers – especially if nvidia – lots of reports on adobe forums about older nvidia drivers causing issues with this

  2. fullmetal says:

    Upgraded the drivers and the problem’s still there. I guess i’ll have to wait for some fix update.

  3. Reimu says:

    Thanks, disabling protected mode solved it for me. Hope firefox and flash will figure out how to get along in near future.

  4. Roy says:

    Adobe have just released an updated version of Flash Player (11.3.300.262) for Firefox to hopefully resolve these problems

    See article https://techlogon.com/2012/06/21/june-2012-update-for-adobe-flash-player-in-firefox-only/ for details and advice on what to do if this version does not stop the crashes (install Flash 10.3)

  5. MostertKroket says:

    Good job m8!!

  6. josecaldera says:

    ProtectedMode=0 ALSO works for WindowsXP SP2 & FF13.0.1 & FlashPlayer 11.3.300.265 but not with GChrome21.x

  7. mxx says:

    we still have the problem after 3 months!
    we can’t tell all our users to disable protected-mode or downgrade their flash version so I hope Adobe will accept that they did a HUGE mistake and finally fix this bug