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Why Cookies and Site Data are not completely deleting every time I close Firefox?

  • 5 replies
  • 1 has this problem
  • 12 views
  • Last reply by MinimalTech

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Hi. I am using Firefox for years, mainly due to it's increased security and privacy settings it provides. As you can see in the attached screenshots, I have set Firefox in Privacy & Security tab to Strict Tracking Protection and to Never remember history. The problem is that, when I close and reopen Firefox, NOT all cached content gets deleted automatically!

Please see my screenshot of Cookies and Site Data section. You will see that there is 1.1MB of Cached Web Content which is not deleted. If I don't manually delete this content (e.g. every week), the size of it gets grow to a very big number of MB (400-500MB).

Why Firefox is not deleting the Cached Web Content automatically since I told it explicitly to do it by choosing Never remember history?

I am using Mozilla Firefox 76.0.1 (64-bit) on Windows. This happens in all of my PCs..

Is this a Bug?

Hi. I am using Firefox for years, mainly due to it's increased security and privacy settings it provides. As you can see in the attached screenshots, I have set Firefox in Privacy & Security tab to '''Strict''' Tracking Protection and to '''Never remember history'''. The problem is that, when I close and reopen Firefox, '''NOT all cached content gets deleted automatically!''' Please see my screenshot of Cookies and Site Data section. You will see that there is 1.1MB of Cached Web Content which is not deleted. If I don't manually delete this content (e.g. every week), the size of it gets grow to a very big number of MB (400-500MB). Why Firefox is not deleting the Cached Web Content automatically since I told it explicitly to do it by choosing Never remember history? I am using Mozilla Firefox 76.0.1 (64-bit) on Windows. This happens in all of my PCs.. Is this a Bug?
Attached screenshots

Modified by MinimalTech

All Replies (5)

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Location of the cache/cache2 folder; Windows: *C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\ Mac: ~/Library/Caches/Firefox/Profiles/ Linux: ~/.cache/mozilla/firefox/

Close Firefox. Open your file browser to the above, and remove the folder.

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Hi FredMcD, there are 2 folders inside \Profiles\:

1) (random-code).default-release

2) (random-code).default

The folder No.1 has 7 sub-folders inside and the folder No.2 is empty in the PC I am using right now (Windows 10 Pro). Which folder should I delete?

Also, if I delete my profile folder, am I going to loose my Bookmarks and the Settings I have made in Firefox? Is it safe to delete these folders?

Modified by MinimalTech

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Hello MinimalTech,

If you reopen tabs automatically the next time then Firefox stores cookies from those tabs by default as part of the session data in the sessionstore.js file.

http://kb.mozillazine.org/Session_Restore

You can set the browser.sessionstore.privacy_level pref to 2 (never) or 1 (non-HTTPS) on the about:config page to disable saving cookies via session restore.

The browser.sessionstore.privacy_level_deferred pref is used when you do not reopen the previous session automatically via "Show my windows and tabs from last time" and uses the same values.

http://kb.mozillazine.org/browser.sessionstore.privacy_level

Hope it works !
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If you use Firefox in Private Browsing mode then all session data is stored in memory and purged automatically when you close Firefox, so there is no need to clear data stored in the profile.
If you still have data stored on the hard drive like in the disk cache then you can't remove this data when you are in PB mode (it is there waiting for you if you start Firefox in regular mode).
You would either have to start Firefox in regular mode or clear this data yourself on the hard drive if that bothers you.

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@Shashank Shekhar,

no, I do not reopen tabs automatically in Firefox. When I finish browsing, I close Firefox from the classic "X" button of it's window and when I open it again, I have only 1 tab with my Homepage I have set loaded.


@cor-el,

I am using Firefox with "Never remember history" mode (please watch the attached screenshots). By this, I think I have told Firefox to NOT remember anything. But Firefox "remembers" or to be more specific "forgets" to delete anything from a browsing session on this mode. Specifically forgets to clear the Cached Web Content.

I can clean it of course manually in Private Browsing mode (it is not true that I can't and need to be in regular mode) but that is not the point!!

Firefox must "forget" everything from a session because if it don't do it, then it leaves privacy data exposed...

So, is this a Bug? Or deliberately Firefox forgets to delete the Cached Web Content?