You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox.

Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

I will give that ago. Seems strange that it affected all 3 computers after the Quantum Upgrade.

I take it ai will loose all session data after deleting if the tool is unable to recover it. I can start again if I know that this is the solution and not a known bug in FF.

Twice now helping relatives track down issues in Chrome a site has let Chrome reset all of my firefox tab settings. Why, TF, can Chrome be allowed to do that. I have hit similar pages in FF and IE and they have prompted me and then again if I wish to also modify other browsers. Chrome Nah. Sorry, side rant.

Please do not completely delete the existing session files! You can save them somewhere else for later URL mining.

There was a bug in Firefox 56-57 which could lead to Firefox stopping updates to the session history files -- normally they are updated as often as every 15 seconds. Firefox 58 had a fix to detect when the background process that updated the file had stopped working, and restart it again. However, it's possible that there are other reasons the file stops getting updated which need to be tracked down and reported.

Before you exit Firefox the next time, could you take a peek at your session history files and see how up-to-date they look? Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using 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

In the first table on the page, click the "Open Folder" (or "Show in Finder") button.

Double-click into the sessionstore-backups folder where you'll find the majority of your session history files. In particular:

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session, which should update within 15 seconds of a relevant change, such as navigating a tab to a new page, opening a new tab, closing a tab
• recovery.baklz4: a backup copy of recovery.jsonlz4 that is updated with a further 15 second lag

How current are the files?

Some users modify this 15 second interval because they read advice about how frequent data writes will ruin their SSD drive (this may be an overblown concern). If you ever did that, you would see it here:

(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.interval preference is bolded and "modified" you can determine the number of seconds by dividing by 1000:

• default of 15000 => 15 seconds
• 60000 => 60 seconds (1 minute)
• 180000 => 3 minutes

To reset to default, you can right-click > Reset the preference.

OK, this is still an issue on all of my machines.

It looks like it is a pinned tabs issue.

I open firefox and one of my URLs is http://explosm.net/comics/4876/

That's probably a week old I skip through them and on next restart it reverts.

They revert to the pinned tab loaded at startup but if you are moving news items, comic strips or other items along your pinned tabs also need to be updated at save.

Do you mean you have to click each of the pinned tabs and load them during each session, otherwise, they lose your spot on the page at the next startup?

I don't know why that would be... but I don't use pinned tabs myself.

No I have several pinned tabs.

Mynews/article33 Mycomic/Jan04

I will keep firefox open for days and move these onward each day to

Mynews/article75 Mycomic/Feb04

On closing and re-opening Firefox the URLs of all my pinned tabs revert to the old values, not the most recently visited pages.

Non pinned tabs seem to retain their URLs at browser close but not pinned tabs. I can see why this is a decision that may have been made if people complained that bbc.co.uk pinned didn't revert to bbc home after restart but it has only happened since quantum so there must be an option to save the location of pinned tabs.

I follow several incremental sites and now have to click past every single page since quatnum to get back to present or cloick end and watch them in reverse.

Okay, that's all new to me.

What if you un-pin/re-pin a pinned tab with the new URL, does that one stick or does it still revert? Perhaps then the new one will become the permanent pinned tab URL.

Yes. Unpinning and re-pinning re-sets the restore point for that tab.

I really don't want to have to remember to do this every time I re-start the browser however. At least next week I'll have less pages to wade through before I find the end again.

I don't know if this will help;

Type about:preferences#privacy<enter> in the address bar.

The button next to History, select Use Custom Settings.

Turn on Remember My Browsing And Download History At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on ONLY Cache and Form And Search History leaving the others off.

It was worth a try but no, increasing the things deleted at close did not help retain the URL of pinned tabs.

I can sort of see the logic.

If your pinned tab is news.bbc.co.uk then you may want it to go to the main site on open.

It just never used to do this and over half of my pinned tabs are reliant on being at the page they left of on as prgressive day to day updates.

It would be nice to find the option to make pinned tab URL remembrance remember the URL when closed rather than the URL when pinned.

It definitely behaved this way before the quantum update and the Mozilla team are better at most at making it an option when fundamental functionality changes are introduced.

Bodestone said

It would be nice to find the option to make pinned tab URL remembrance remember the URL when closed rather than the URL when pinned.

I think I see it now. (I don't use pinning) The tab that was pinned is recorded. And that's the tab that will open. If you want to follow something like that, unpin, then repin.

That is not a viable solution and was not the way it worked before quantum. I do not want to have to unpin and repin 6 tabs before closing FF. I didn't have to do so before.

There needs to be an option to remember pinned tab URL from either PinnedURL or ClosedURL.

The basic functionality has changed from the latter to the former so needs to me made an option.

I have 8 pinned tabs at home and 6 at work.

Maybe someone more familiar with pinned tabs could take the conversation. On the other hand it's spreading the knowledge. I do thank you for your help though. You have directed me to test things I had forgotten to test.

I can prvide specific URLs if need be as it is an exactly reproducable issue.

Cheers, Rob.

I called for more help.

I realize this wasn't a very exhaustive test, but for what it's worth:

I opened the pinned tabs help article, pinned it, then clicked through about a dozen other pages on this site. Then I left it alone and went on with my day. Before shutting down, I captured a screenshot of the back button right-click context menu. After I exited and restarted Firefox, the pinned tab showed that last page and the back button context menu listed back history to the usual depth (max. 10 pages).

I have Firefox set to restore my entire previous session at startup, in case that is a factor.

It actually does not even seem consistant:

URL after re-pinning: explosm.net/comics/4886/ Navigate backwards and forwards a few times and go to last comic Let the page sit at explosm.net/comics/4803 Close and re-open FF URL of tab is now explosm.net/comics/4889

As I say I am noticing this on 3 instances of Firefox on 3 different PCs. I am not syncing tabs.

Are that always pages that are opened via a specific URL or probably pages opened via XHR in a fixed page?

What are the current startup settings?

"Show my windows and tabs from last time" is always safest.

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit