It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Delete the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost, so you will have to create them again (make a note or bookmark them).

• http://kb.mozillazine.org/Multiple_profile_files_created

It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Hah! That is VERY apparent. It is NOT a 'possibility' it is a fact. It is all well and good to say 'this is what you should do' but this does not fix the problem when it occurs repeatedly.

Equally, the "make a note or bookmark them" is of no use at all when an error such as this happens without warning. This is a HUGE PROBLEM for Firefox when there is no ability to automatically recover from this and the proposed 'answer' is effectively a kludge requiring manual intervention on the part of the user. Many users (like me) use the Group Tabs function to separate their active session into logical work areas; one for basic admin (mail, news, social networks etc), one for a research project (blogging, writing an article/essay/thesis), one for job searching... etc. These groups are likely to be exceedingly dynamic within a session and across sessions with additions and deletions galore. Saying 'you have lost them, start over' is stating the obvious but is neither practical or of any use whatsoever toward providing a solution which PREVENTS this happening again, and again, and again.

'make a note' - What? Jot the link down on a Post It note?

'bookmark the tabs' - If i am performing research I will open and close perhaps 20+ tabs in an hour and retain only those most pertinent or relevant. Some of these tabs will be needed across sessions. Were I to repeatedly bookmark all the tabs I then have a version control nightmare requiring repeated manual action separate from my browsing and research.

In this case, I (the 'craftsman' - good or bad) have every right to blame the tool (Firefox) and the 'answer'. Firefox has a problem. The 'answer' says there is a problem which occurs without any warning so start over. My point is" Firefox should NOT allow a significant change to the current user configuration to occur. This is equal to all bookmarks being completely lost or (with a separate piece of software e.g. Word or GIMP etc) a file vanishing from the system. It is NOT acceptable for this to happen when there is no way to EASILY revert to a prior version and/or perform a backup of the current session.

HOWEVER!!! Your response did point towards the CAUSE of the problem. The last link you provided points to the culprit being anti-virus software. Looking back at my scheduled maintenance records for my computers, the times when Firefox has lost the Group Tabs and when the virus scans have occurred have been one and the same. i.e. it is the anti-virus software which is the 'culprit'. Now I know I can prevent this happening on several computers EXCEPT on those where I do not have permission to change the scan options due to company/organisation policy.

BUT...

The average Joe or Joanna user will not. Asking them to 'fix' a clear weakness in Firefox when they may not even have access or the knowledge/skills to adjust the scan options of their AV software is NOT the answer. In addition, this does not provide a recovery solution. I can back up my profile and export/import my bookmarks but (unless someone knows a method) cannot 'keep tab of my tabs' (so to speak). is there an app for that? i.e. a method to archive and restore a user session.

I also find it very frustrating when I have to trawl back through the history (and often miss something) to restore all the open tabs I have.

Interesting that a virus scan has been identified as the cause of losing tab groups ... I ran a scan just before losing all my tabs. |Being able to back up and restore current tab groups would be a tremendous help in overcoming this shortcoming.

App (pinned) tabs and Tab Groups (Panorama) are stored as part of the session data in the sessionstore.js file in the Firefox profile folder.

You can make a backup copy of the sessionstore.js and restore that copy to get that saved session back.

• http://kb.mozillazine.org/sessionstore.js

Thanks for that. Weirdly, I did a microsoft update (12 updates) and uninstalled my tablet driver. When I re-started, my old session came back - don't know where it was hiding or why it failed to come up on the previous re-boot !!

This WOULD probably be a good solution but it does not overcome the issue. The issue is that the virus scan is a (very necessary) background system process where the user (me) has no control over when an exclusive lock is placed upon the file.

For personal use, yes, then a user could possibly do something about it. For use on a system where user access control for the specific OS is enforced then: 1. The virus scan activity cannot be controlled. 2. There is no access to the system settings like the Mozilla folder. Equally, this assumes a specific level of technical knowledge and places an administrative burden upon users who may or may not be technically proficient and/or able to remember to frequently backup the profile. Add to the mix the fact that the loss of grouped tabs does not happen on a fixed interval (only when the scan occurs at the same time FF is trying to write to the file i.e this could be ANY time).

Grouped tabs is an incredibly useful feature which I, and I am sure many others, use to segment their browsing into logical areas. It is essentially emulating how a desktop is organized with a series of folders which can be opened for activity to occur. Without it? Do I revert to multiple instances of FF and all the associated issues this creates? Do I create an 'Open All In Tabs' scenario which again places a heavy load on the user.

Now perhaps I will throw another 'issue' into the mix which is ultimately what I think would be the solution to the problem and something which MAY be workable. Perhaps someone could advise on the specific technical aspects of this. The facility to synchronize across multiple computers clearly holds a 'master' copy of the current active session and is stored online. Is there an option to auto-synch the current active session with this as a background process (timed intervals?) and can the user be prompted (or have an option set) to restore from the 'master' session stored online? This would provide a good safety net for even the most basic of users as well as giving any sysadmin an option to reduce support time on a crashed session.

Also, what about utilizing the 'Synchronize' process as the PRIMARY location for the sessionstore.js? The person is online anyway and would/could auto-login to retrieve the last browsing session. This would solve several of the know issues with the sessionstore files....

Just a thought or two.