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

Flash Player Sandbox for Firefox (Public Beta) Launched by Adobe

Disabling Sandboxed Flash Player in Firefox

UPDATE August 25, 2015: Firefox now offers a setting within Flash Options to disable or enable Protected Mode.

Click on Menu > Add-ons > Plugins > click on ‘Options’ for ‘Shockwave Flash’ and uncheck the tick button for the ‘Enable Adobe Flash protected mode’.

Enable Flash Player Protected Mode Option for Shockwave Flash Plugin

UPDATE Feb 9, 2015: Instead of below procedure, you can also do this:

Visit about:config, find and change ‘dom.ipc.plugins.flash.disable-protected-mode‘ preference value to ‘true’ ( if it already showing the same you don’t need to make any change).

From the first beta release notes PDF of Flash Player Protected Mode(PM) 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 the settings defined in it to manage its functionality.

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



mms cfg file location

How to Turn off/disable Protected Mode in Adobe Reader X

Configuring mms.cfg file: To locate the mms.cfg file, you need to enter the above path in Run command and open that file with Notepad and add “ProtectedMode = 0” in the third line. (There are two settings that are already pre-exists in mms.cfg file, they’re:  “AutoUpdateDisable=0” and “SilentAutoUpdateEnable=1” (the values for these settings may be different to you, which we can not confirm)).

entries in mms.cfg file

That’s it! Flash Player’s Protected Mode has been disabled for Firefox. When troubleshooting is over, turn it 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.

How to Disable Flash Player Sandbox in Google Chrome

Update: After installing Flash Player 11.3, we’ve experienced  the crashes. Make sure to add ProtectedMode entry as it is mentioned above including spaces. If you can’t find mms.cfg file in your computer in the above mentioned directory, you can download that file from the below link.