Hello! By default Firefox doesn't restore the previous session. You just have the button "Restore Previous Session" at the bottom of the home page. Preference browser.sessionstore.enable doesn't exist anymore.

Now you can set browser.startup.page preference

• Value = 0: start with a blank page (about:blank)
• Value = 1: default (about:home)
• Value = 2: last visited page
• Value = 3: previous session

Hope you'll find an issue in these parameters to fix your problem!

Hello. By default Firefox *DOES* log sessions in case you want to restore them. In the profile directory you will find a directory named sessionstore-backups containing data that I simply don't want Firefox to collect.

Is there a way to prevent this behaviour?

According to me, the easiest way is to use Private Browsing. To active it, enter the following URL: about:preferences#privacy and change the parameter of Firefox will: to Never remember history or Use custom settings for history to customize. You'll be sure any data'll be collected!

I can't recall why browser.sessionstore.enabled was removed, but it may be because Firefox wants to be able to restore the session after a mid-session update or to go into its Safe Mode. The session history file might also be used for windows and tabs you close during your session that you might want to re-open.

There are numerous preferences starting with browser.sessionstore that may limit what is stored in session history. For example, to not store session cookies in the file, you can change the value of these preferences:

browser.sessionstore.privacy_level => 2 browser.sessionstore.privacy_level_deferred => 2

To reduce time spent maintaining the file, you can extend the update interval from as often as every 15 seconds (this value is in milliseconds, so 15000 = 15 seconds) to something much longer such as once per minute:

browser.sessionstore.interval => 60000

Thanks, it's interesting. But anyway, when I set the option browser.sessionstore.privacy_level to 2, Firefox still saves a huge amount of private data.

This is not only a privacy issue: the browser consumes CPU and memory to do something I don't need - something that I've already told Firefox not to do when I set "about: blank" as my default homepage.

This seems a bug to me.

To request that the feature to disable it be re-added to future versions of Firefox, you can try one or more of these:

• Input site: https://input.mozilla.org/feedback

• Developer mailing lists: https://lists.mozilla.org/listinfo

• Bug tracking system: https://bugzilla.mozilla.org/enter_bug.cgi
  • See: https://developer.mozilla.org/docs/Mozilla/QA/Bug_writing_guidelines
  • Bugzilla Etiquette

Thanks, I'm not new to BugZilla - yet I thought there was an easier way to disable the session restore....

Bug filed:

https://bugzilla.mozilla.org/show_bug.cgi?id=1176874

Thanks anyway.

If you set the settings to clear history on close this would remove history and sessions afaik.

You can also set the browser.sessionstore.max_serialize_ (back, forward) prefs to 0.

• browser.sessionstore.max_serialize_

Hello.

@guigs2: one problem is that I absolutely don't want to lose the browsing history, that I need very much.

@cor-el: and the other problem is that I need to be able to go back/forward in my browsing session. I simply don't want this data to be written, I can obviously accept that this data are somewhere in RAM while I'm browsing.

IMHO It's a security/performance issue. It's not the first, it will not be the last.

The browser.sessionstore.max_serialize_ prefs only specifies how much back and forward history is stored in the sessionstore.js file and not the what you can use in the current session (browser.sessionhistory.max_entries). The default for back history in sessionstore.js is 10 and the forward history is unlimited (-1).

So, if I set 0 to both these preferences, the sessionstore.js is not created? This could be a solution.

The file is still created because you can't disable Session Restore, but will have less content and only have the information of currently visible tabs.

There is a lot of data stored in the file and some data can be disabled like the back/forward tab history and cookie data (browser.sessionstore.privacy_level).

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

Data for Recently Closed Tabs and Windows is stored as well.

• http://kb.mozillazine.org/browser.sessionstore.max_tabs_undo
• http://kb.mozillazine.org/browser.sessionstore.max_windows_undo

The only way to prevent session data getting stored is Private Browsing mode.

You can use an extension to get Private Browsing mode support per tab.

• Private Tab: https://addons.mozilla.org/firefox/addon/private-tab/
• Private Browsing mode tabs get a dashed underline
• You can toggle Private Browsing mode on/off via the right-click context menu of a tab

Hi cor_el, I know very well the PB mode (after all the articles we have translated in SUMO).

Yet I don't think that I'm completely satisfied with this solution.

Underpass said

Bug filed: https://bugzilla.mozilla.org/show_bug.cgi?id=1176874 Thanks anyway.

It may help if the bug were confirmed and so new instead of unconfirmed. That possibly will need it to be marked as a RFE and would probably help if the bug removing the pref could be cross referenced. Alternatively the bug may be an unintended regression, but that is probably unlikely.

It may be useful to try the forums/mailing lists as mentioned above ^{#answer-744969} to get background information on the change.