How to Disable Protected Mode of Flash Player in Firefox

by Venkat eswarlu on June 9, 2012

in How to,tips and tricks

Today we’ve covered that Flash Player 11.3 has been released by Adobe with Protected Mode by default for Firefox, Sandbox Flash Player running in Firefox prevents your system from attacks from malicious SWF files. But if you’re facing issues with Flash Player Protected Mode in Mozilla’s browser you can disable it to troubleshoot the problem.

Disabling Sandboxed Flash Player in Firefox

From first beta release notes PDF of Flash Player Protected Mode for Firefox we came to know that PM can be disabled by adding a setting “Protected Mode =o” to mms.cfg file. Here is what that PDF states

“The Protected Mode sandbox could cause compatibility issues with existing Flash content on the web If however, you see a potential problem that may be related to Protected Mode, you can disable Protected Mode with the following setting in your mms.cfg file:
ProtectedMode = 0“

What is mms.cfg file?

We’re assuming by default when Flash Player installed on your system it places mms.cfg file and Flash Player uses settings defined in to manage its functionality.

mms.cfg file is a a text file, it is located in the following system directory


mms cfg file location thumb How to Disable Protected Mode of Flash Player in Firefox

Configuring mms.cfg file:  All you need to do is enter the above path in Run command to locate mms.cfg file, open it with Notepad and add “ProtectedMode = 0” in the third line, where there are already pre-exists two settings “AutoUpdateDisable=0” and “SilentAutoUpdateEnable=1” these values for these settings may be different for you which we can’t confirm.

entries in mms.cfg file thumb How to Disable Protected Mode of Flash Player in Firefox

That’s it Flash Player’s Protected Mode has been disabled for Firefox. When troubleshooting is over turn PM back on, that’s what Adobe recommends  “Adobe recommends that you keep Protected Mode enabled at all times”.

How to Confirm Flash Player Protected Mode was disabled for Firefox?

When Protected Mode has been turned on you can see two child processes of “FlashPlayerPlugin_11_300_257.exe” running in the Task Manager you won’t see them when protected Mode is disabled except running of Firefox.exe and Plugin-container.exe processes.

To enable Protected Mode again remove “ProtectedMode = 0” line we added earlier in mms.cfg file and save the changes.

Update: We’re experiencing Firefox crashes (using Firefox 14 beta ) after installing Flash Player 11.3.  Makes sure to add ProtectedMode entry as it is mentioned above including spaces. If you can’t find mms.cfg file in your Computer in above mentioned directory, you can download that file from below link.


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{ 7 comments… read them below or add one }

iaTa July 8, 2012 at 6:10 am

On Windows x64 the location is actually:



big a4 November 3, 2013 at 8:17 pm

dude. im so glad i saw your comment…


arddy January 25, 2013 at 9:27 am

Just as a tip, your ‘how to’ guide for this is 8000 words too long and in the wrong place.

If you’re going to be that detailed, which a lot of users aren’t after, then you mind as well get it all of the info, including the one iaTa has mentioned.

Instead of ‘not’ doing a redicously detailed version like you have, split it.


swiss April 25, 2013 at 9:02 am

It would not let me save that file :(


miss October 26, 2013 at 2:57 pm

This is exactly the info I needed & Adobe does not provide this kind of tech support. The problem still exists in Firefox 24 with Flash 11.9

It takes Adobe years to fix bugs; I wish every web site would stop using Flash


tm4 November 14, 2013 at 4:24 am

If you are experiencing rights problem (could not save the file), just Right Click on the file -> preferences -> Security (2nd tab) -> Button Edit -> Choose your profile (Users ) -> check allow full control (first checkbox) -> OK


Frank O December 3, 2013 at 1:02 am

It’s probably a good idea to use a zero character when you mean zero, and not the letter “o”. Anyone copying & pasting would be screwed.


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