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How group policy work for browser.cache.disk.parent_directory

  • 9 replies
  • 1 has this problem
  • 84 views
  • Last reply by Mike Kaply

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Some years ago I pointed my Firefox cache drive to H:\Firefox. When I updated to 68esr I set the value in the GPO to the same folder. about:config shows the preference as locked.

Recently I decided to move the cache folder to the same drive as the profile folder. So I edited the group policy to point to F:\users\Tanya\Firefox. Updated the group policy and opened firefox. It continued to use H:\Firefox.

So set the policy to not configured and about:config showed h:\firefox. So as a test I set the group policy to iamcountessconsuelabananahammock (Not even a valid path name). No complaints, but firefox continued to write to h:\firefox.

So it seems the only purpose of the group policy is to lock the value, and the content of the GPO is not relevant at all. Is this by design

Some years ago I pointed my Firefox cache drive to H:\Firefox. When I updated to 68esr I set the value in the GPO to the same folder. about:config shows the preference as ''locked.'' Recently I decided to move the cache folder to the same drive as the profile folder. So I edited the group policy to point to F:\users\Tanya\Firefox. Updated the group policy and opened firefox. It continued to use H:\Firefox. So set the policy to not configured and about:config showed h:\firefox. So as a test I set the group policy to iamcountessconsuelabananahammock (Not even a valid path name). No complaints, but firefox continued to write to h:\firefox. So it seems the only purpose of the group policy is to lock the value, and the content of the GPO is not relevant at all. Is this by design

All Replies (9)

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Does the new cache folder that you point to actually exist because that is necessary and this directive might be ignored when the cache folder isn't found ?

You can also try to remove the cache folder on the H drive to see what folder Firefox will use by default.

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As I said, I was moving my folder from H: to F: when I discovered this. On a different PC I started testing v78.3.1 (That's a whole other can of worms). On this PC I didn't set a value in about:config, I just used the GPO.

Firefox continued to use the default in %APPDATA%.

I removed the value from the v68.12.0 PC via about:config and observed exactly the same behavior.

I removed the folder and set the GPO and removed the about:config preference. Firefox created a cache folder in %APPDATA%.

I removed the folder again, and removed GPO as well. Firefox created it in %APPDATA%.

I removed the folder again and put maryhadalittlelamb in the GPO. Firefox created the default cache folder in %APPDATA%. The GPO value had no effect at all.

So, without a doubt, the group policy value does nothing more than lock the about:config preference if it exists. Setting a GPO value does not add the preference in about:config, not does it try to create a folder. It's value has no bearing on what folder is used. It makes sense to put a valid value there for informational purposes, but other than that the value serves no useful purpose.

To specify an alternate folder location one MUST set it from about:config, then apply the GPO to lock it.

As I'm not really concerned about people playing with this (They either don't care or don't know how), the GPO setting is of no use at all.

I wonder how many other settings work the same?

Modified by TanyaC

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This is fixed with the new Preferences policy.

The cache directory has to be a user pref that persists across invocations.

The new Preferences policy allows that.

https://github.com/mozilla/policy-templates/blob/master/README.md#preferences

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Mike Kaply said

The cache directory has to be a user pref that persists across invocations.

I'm not sure what that means. But the behavior I'm seeing in 68.12 and 78.3 is that the GPO does nothing other than lock the setting value. A user cannot edit it via about:config. The value in the GPO from the tests that I've done mean nothing, other than perhaps being for informational purposes.

What I initially thought the policy would do is override the preference in about:config.

FWIW, I'm applying the policy via gpedit.msc, not editing the registry or any other method.

Anyway, it's not a problem. I was curious if the behavior was intended or not. I'm not going to use the group policy, I'll just edit it via about:config as that has to be done before setting the GPO anyway.

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I assume you're using the old Preference that explicitly says "browser.cache.disk.parent_directory"

what I'm saying is that doesn't work and you shouldn't use it.

If you grab the latest ADMX files:

https://github.com/mozilla/policy-templates/releases

There's a new policy at the top level called "Preferences" (Not the category, a standalone policy).

You can paste this code in there:

{

 "browser.cache.disk.parent_directory": {
   "Value": "SOME_NATIVE_PATH",
   "Status": "user"
 }

}

and it will work:

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Mike Kaply said

I assume you're using the old Preference that explicitly says "browser.cache.disk.parent_directory" what I'm saying is that doesn't work and you shouldn't use it.

Yes, that is the setting that I am using. It works fine from the about:config page, just not the group policy.

I was going to add a couple of pics to demonstrate, but I don't think there's any need at this point.

Anyway, I will refrain from using the group policy.

Thank you.

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> Yes, that is the setting that I am using. It works fine from the about:config page, just not the group policy.

Yes, that's why I marked it as not working in the group policy.

To use it in group policy, you have to switch to the new Preferences policy (not the old one).

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If you mean the group policy templates that are for FF78esr - the behavior is the same. I downloaded the latest templates less than a week ago. I discovered this issue when testing FF78esr, then went to another PC see if it was the same in FF68esr Anyway, I shall refrain from using the group policy. It's not a big deal.

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You can definitely use group policy for this. I've attached an image that shows how the new preference policy works.

For it to work, you need to make sure you don't have any preferences in the old Preferences (deprecated) category.