Bump, just auto-updated 56.0.1 x64, still has the same issue...

I don't remember seeing this button... I wonder whether it is a built-in feature or an add-on feature. What does the button do (when it works)?

jscher2000 said

I don't remember seeing this button... I wonder whether it is a built-in feature or an add-on feature. What does the button do (when it works)?

Hi,

    Thanks for the reply.  In the screenshot below I show where this button is.  I think it's a built-in button, since I almost never customize my Firefox.

    When it used to work prior to v56, the drop down list of recently closed tabs were cleared.   Since the v56 update, this list remains there after clicking on the Clear 'Closed' List.

Hmm, I haven't seen it before and I don't know what is generating it. Do you have any tab-related, session-related, or history-related extensions? You can view, disable, and often remove extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything that could relate to closed tabs? Anything with that same icon?

If you want to copy/paste your extensions list into a reply for comment, you can do that from the Troubleshooting Information page. Either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Scroll down past "Application Basics" and "Firefox Features" to "Extensions". Then you can select and copy the table that follows (not the entire page, please, that's too much information) using either Ctrl+c or right-click > Copy and then paste it into a reply. It will be messy, but we're used it.

Can you post a list of your extensions as shown on the "Help -> Troubleshooting Information" page?

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

Thanks guys,

    Here is the extension list and its screenshots:

Extensions Name Version Enabled ID Adblock Plus 2.9.1 true {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Kaspersky Protection 5.1.93-0-20170120164436 true light_plugin_448EC0843447455C9DA355B3C2811D6A@kaspersky.com Session Manager 0.8.1.13 true {1280606b-2510-4fe0-97ef-9b5a22eafe30}

I do have installed Kaspersky Total Security 2018 and Adblock Plus + Session Manager plugins

Okay, I think it's part of Session Manager, they have a screenshot of that button/menu on the extension's page on the Add-ons site:

I see someone has reported the problem here already:

http://sessionmanager.mozdev.org/bugs.html

But when I click to read the details for bug #26428, no one seems to have offered a solution or workaround yet.

That's all I know.

Thanks, then it's a known problem associated with the session manager add-on. My system is win 7 x64 SP1 ultimate.

Not sure if Session manager will last starting from v57 tho. Cuz if it won't last, there is no point to fix.

It's useful to save my 300+ tabs in the case of a crash. But its default backup frequency is too aggressive = every 15 seconds, can easily write 40GB of data to my SSD daily. I changed it to every 3600 seconds.

The legacy Session Manager extension definitely won't run in Firefox 57. I don't think that the new WebExtensions API allows extensions to do anything with the automatically created session history files. However, I think they could build their own session history by tracking all of your tabs as you open/close/navigate them. Might be more work than it's worth.

As a test, I created a Windows scheduled task that would make a backup copy of my live session history file (now called recovery.jsonlz4) every hour using a script. However, I changed it to daily because I never used the backups. I think each person's individual tolerance for risk will determine their personal backup strategy and of course privacy is a consideration -- people might not want to have months and months of data on every page they viewed in another backup file.

Does firefox by default do a backup every 15secs just like session manager? Without session manager, I remember I could lose all tabs upon a crash.

I think this settings is saved in browser.sessionstore.interval, with or without session manager

DraculaxAOE said

I think this settings is saved in browser.sessionstore.interval, with or without session manager

Yes, that is the interval for the built-in session history feature. I set mine to:

browser.sessionstore.interval = 60000

That's 60 seconds x 1000 milliseconds instead of the default of 15 seconds x 1000 milliseconds.

That is the maximum frequency of updating. If nothing has changed, I don't think Firefox bothers to write out the same file again.

Without session manager, I remember I could lose all tabs upon a crash.

Do you have crash recovery enabled? That is the default setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste sess and pause while the list is filtered

(3) If the browser.sessionstore.resume_from_crash preference is bolded and "modified" or "user set" to false, double-click it to restore the default value of true

(3) If you want Firefox to display a list of windows and tabs after a crash so you can choose what to restore, instead of trying to restore everything automatically, double-click the browser.sessionstore.max_resumed_crashes preference and edit the value to 0 (that's a zero) and click OK

Assuming that is all fine:

Reasons that Firefox might lose session history even if you set Firefox to start up with your previous session windows and tabs (see: Startup, home page, tabs, and download settings):

(1) Session history files corrupted by the crash (I think it's rare that both recovery.js/jsonlz4 and recovery.bak/baklz4 get so corrupted that you can't restore after a crash)

(2) Firefox set to clear history when it closes (Browsing history category)

(3) You have utility software set up to clean out Firefox data between sessions or at Windows startup

An additional reason that Firefox might lose session history when you set Firefox to start up with your home page and only restore your session manually is this scenario:

Firefox was closed and some other program launched a page in a new window for some reason. You forgot that this was the only Firefox window and you close it without restoring your previous session. Boom. Previous session gone.

Ah, now I remember. You mentioned that some other program launched a new window and i closed it after the main window. This is probabaly why I started to use the session manager in the first place, cuz I think it is able to recover from several different saves.

Is the max value for browser.sessionstore.interval only 60 seconds, so setting it to 3600 seconds is the same as setting it to 60 seconds? But it's good to know that only recently changed tabs are backed up, instead of over 300 tabs that I kept.

DraculaxAOE said

Is the max value for browser.sessionstore.interval only 60 seconds, so setting it to 3600 seconds is the same as setting it to 60 seconds?

I don't think there is a maximum value. However, 3600 is very short because the value in about:config is in milliseconds (1/1000 of a second). 3600 seconds (once per hour) would need 3 more zeroes: 60 * 60 * 1000 = 3600000.

Personally, I think that's too infrequent if you tend to browse very actively, as opposed to watching long movies most of the time. How about once every 5 minutes as a compromise? 5 * 60 * 1000 = 300000.

But it's good to know that only recently changed tabs are backed up, instead of over 300 tabs that I kept.

Actually, that's the problem. If there is any change to the pages in your tabs, when the update interval comes up, the whole file needs to be rewritten. That's why people are anxious about their SSDs, and people with spinning hard drives may experience some performance drag, with the default value of 15 seconds (15000 milliseconds).

Exactly, I did set mine to 3600,000 ms, but in session manager it's in secs so 3600. I tend to leave firefox on for hours, and don't usually open a lot of new pages at once, so a backup on hourly basis is ok.

I remember I monitored the disk write due to firefox at the beginning of this year. It was at least 20GB(maybe up to 40GB) per day with the default settings

Is firefox able to recover multiple sessions, in the case of an unwanted window opened and erased the previous session info?

DraculaxAOE said

Is firefox able to recover multiple sessions, in the case of an unwanted window opened and erased the previous session info?

No, Firefox only stores one session at the time, plus the occasional snapshots made when Firefox updates.

Ah...

Wish FF v57 can really save multiple sessions to prevent overwritten session from happening, so one doesn't need to use session manager, as it won't be available in v57

You do not need Session Manager to keep one session history file for crash recovery or to extend your session. Session Manager is a handy backup tool in case the session history file becomes corrupted, but of course you can make backups through other means. Where Session Manager is most unique is making it easy to switch among multiple session history files.