I wonder whether there is a timing problem with Firefox trying to clear the cookies before the Flash plugin is shut down. If you forcibly kill the Flash process before exiting Firefox the first time, does that make any difference?

TEST: In the Windows Task Manager, Processes tab, look for one or more Flash processes and the plugin-container.exe process, and End those before exiting Firefox. Any difference in whether the entries are successfully cleared?

Not a solution or even a practical workaround, but could provide some insight.

Thank you for your reply.

I suspected a timing problem (I read about the issue coincidentally when looking at the Better Privacy add-on - see my comments below) but did not know how to test it. I followed your suggestion (exact steps listed below) twice and got the same result - the Flash cookies were cleared the first time around.

1) Control Panel -> Flash Player -> Storage tab -> Local Storage Settings by Site... button -> confirm that the list is empty

2) Exit the Flash Player Settings Manager

3) Launch Firefox -> go to www.hulu.com and click on a video to start it playing

4) Relaunch Control Panel -> Flash Player -> Storage tab -> Local Storage Settings by Site... button -> confirm that the list shows www.hulu.com, 0 bytes, Block

5) Exit the Flash Player Settings Manager

6) Go to www.yahoo.com (just to get away from www.hulu.com, which has the Flash content)

7) Windows Task Manager -> kill plugin-container.exe process

8) Exit Firefox

9) Relaunch Control Panel -> Flash Player -> Storage tab -> Local Storage Settings by Site... button -> IS EMPTY

The timing problem is mentioned on the Better Privacy add-on page https://addons.mozilla.org/en-US/firefox/addon/betterprivacy/ and I believe is one of the reasons Better Privacy offers an option for deleting LSOs on FIrefox startup (in addition to on exit).

As you mentioned, the kill plugin-container.exe method is not practical. And the Better Privacy clear on startup functionality is good, but still does not address the fact that the history is maintained on the computer until Firefox is launched again...

Out of curiosity, are you able to replicate my original condition?

I don't clear anything at shutdown so I'll have to create a new profile to test. After hours.

Great, thank you! I look forward to your results.

Assuming that you have the same outcome, what, if anything, is Mozilla going to do to address this privacy issue? Should a bug report be filed?

Thanks again.

Hulu was reluctant to play with all Flash local storage blocked (maybe once out of 10 tries).

When I conduct the experiment with YouTube, the entry was cleared the last few tries.

In one case where it was not cleared (not sure which site it was), there appeared to be an additional persistent Adobe Flash process after Firefox closed (distinct from the FlashPlayerPlugin processes). I'm not sure what triggered that or what eventually shut it down.

Have you tested in a clean profile?

I'm not sure exactly how to go about building a "clean profile" - can you explain or point me to directions?

First close Firefox, then from the Windows Start menu > Run

firefox.exe /ProfileManager

You can create new profiles and also use this dialog to switch between profiles. Note that it only works when all Firefox windows are closed; if Firefox is running, it just opens a new window.

I will give it a go later and report back - thank you.

See also:

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

• https://developer.mozilla.org/en/Command_Line_Options

Ok, so I created a new profile and followed the steps I spelled out in my first post several times - each time the Hulu flash cookie was cleared the first time I closed Firefox.

So what would you recommend I do next to get to the bottom of the behavior in my current profile? Should I go about disabling my extensions and plugins one by one and repeating the test each time?

Thanks again so much for your time and help.

PS: I never have a problem with Hulu playing with my flash local storage set to zero - interesting that you do...

I'm not 100% certain it's an extension, but you could disable them all in one go by starting Firefox in "Safe Mode". First, use the profile manager to start your normal profile, then use

Help > Restart with Add-ons Disabled

This disables extensions and overrides some settings. Does that make any difference?

Starting in safe mode caused the flash cookies to be deleted on the first exit.

What do you recommend now please?

Incidentally, I have 2 virtually identical laptops, running the same versions of Firefox and virtually all of the same plugins and extensions, and they both behave exactly the same way in terms of this flash cookie issue.

Safe Mode doesn't deactivate plugins, I don't think, so you can set those aside for now.

I suggest disabling ALL nonessential extensions. We all tend to accumulate ones which aren't really necessary. You can do that here:

orange Firefox button or classic Tools menu > Add-ons > Extensions category

If the core extensions you really like cause the same issue, then I think you might just have to live with it. Please note that Flash is correctly keeping track of your block setting, so I don't think anything actually is being stored.

Problem solved!! The culprit is the RealPlayer Browser Record Plugin 15.0.6 (which is an Extension, but Plugin is part of the name). When I disabled this Extension, Firefox clears Flash cookies the first time around.

By the way, for a while I did seem to be having a problem with Flash correctly keeping track of my settings. I don't want to pollute this thread but if you don't mind, perhaps I can send you a PM re: some Flash questions?

Thank you so very much for your help!!!

Good to hear you found the cause.

Is that the latest updated version of the "Browser Record" add-on? There were some updates in the past few months to resolve other Flash compatibility issues, so I wonder whether they have resolved this one as well.

Regarding Flash issues more generally, I must admit that I do not pay close attention to the details. Posting a new question here or on the MozillaZine forums might help turn up the answers you're looking for.

I was glad to find the cause as well - thank you so much for your help!

Yes, I am running the latest version of the "Browser Record" add-on. I will try to remember to run my experiment again and see if the issue is resolved when there is an update for flash and/or this add-on.

The good news is that I very, very rarely use this add-on, so it's not a big deal to keep it disabled by default and only enable it if/when I am going to use it.

Thanks so much again.