hello, the xpcom error is caused by the windows system restore you've performed. please first try a clean reinstall of firefox and see if you can resolve it that way:

• download the full firefox setup file from https://www.mozilla.org/firefox/all/
• uninstall firefox on the machine
• manually delete all remaining files in the firefox program folder, which usually resides in C:\Program Files (x86)\Mozilla Firefox\
• reinstall firefox

afterwards report back, then we can see what's possible about the tabs...

1- I have done system restores before and NEVER had this problem, so I don't think the system restore is directly responsible for this. Maybe one of YOUR latest updates, which you install in my computer SOO often, is NOT fully compatible with Windows anymore... Note: I do NOT update Windows 7 - Windows allow you to reject updates.

2- Are you sure a re-install will NOT erase my tabs history??? Because recovering those tabs, which is why I did a system restore to begin with, is THE ONLY REASON why I would want to use Firefox ever again at this point!!!

in most cases the xpcom startup error is caused by a system restore that messes up the libraries firefox needs to run. the procedure explained above won't affect your custom settings like tabs since they are stored elsewhere...

OK, Firefox is opening now. About:sessionrestore is empty.

ok, now please proceed like this: enter about:support into the address bar, and click on the button to open the profile folder and close firefox. before you perform any other steps create a backup of all the files in your profile folder starting with sessionstore and the whole sessionstore-backups folder into a secure location.

what you could try now depends on the relevant files that you have present and not tampered with yet:

• if there is a sessiostore.bak from before the problem you could open it with a text editor, copy its contents and paste them into this webservice: https://firefox-session-restore.herokuapp.com/
• look into the sessionstore-backups folder and sort its contents by date. copy the newest file, put it directly into the profile folder, rename it to replace the sessionstore.js file and try if you can get the old session restored when you open the browser. if not close firefox and try it with the next file from sessionstore-backups & so on...

The 4 sessionstore available are from 2011 & 2014, with exception of a sessionstore.js.bak from 3/2/15 that I tried to rename earlier. Renaming is working now, but your 2nd solution does not work. About:sessionrestore is still empty!

That webservice is giving me an error message after taking a long time

Note that a Windows System Restore includes .js files, so doing such a restore will revert the sessionstore.js file to the version of the date that you restored. You would have to undo this restore and save a backup copy of the sessionstore.js file.

An alternative could be to use a utility to inspect restore points to retrieve the sessionstore.js file.

• http://nicbedford.co.uk/software/systemrestoreexplorer/
• http://www.shadowexplorer.com/

1- Windows System Restore CANNOT be reverted!

2- I can assure you that I had a very healthy sessionstore.js on 3/2/15. I remember the changes that I made at that point and I had to reboot to make then, recovering all my open tabs at the time. SO why there is NO sessionstore.js under the Profile Folder after System Restore ???

3- The herokuapp retrieved what seems a VEEEEERRY LONG list of just about every webpage I visited last year AND CLOSED, including multiple pages within the same website... rather useless, since NONE of them are pages I had open at the time of the incident.

Doing a Windows restore should create a restore point automatically.

Oh Funny that Windows prompts saying that the System Restore can't be reverted right before it does it.

So do you suggest for me to revert to the point where my tabs were as gone as they are now? There wasn't a sessionstore.js under the Profile Folder either. I looked.

I'm on Linux, so I don't know how this works in current Windows versions.

If there isn't a restore point and also no previous version of the sessionstore.js file available then your changes to get back that session look quite low. That is one reason to be very cautious with doing a system restore as you can't predict what files get reverted or removed in case Windows thinks that they shouldn't be there.

Did you give the two programs I mentioned above a try?

Haven't tried those yet.

I'm on Windows 7. Before I did the Restore yesterday, I looked at the Profile Folder and saw just the same 7 sessionstore files I see now. I deleted two of them sessionstore-1.js and sessionstore-2.js dated 2011. The others are just that old, with exception of one: a 1K sessionstore.js that is supposed to be in the Profile Folder but I can only see it when I search for sessionstore in the file manager AND it doesn't get replaced when I rename the .bak. I tried right-clicking > restore previous version, but only previous version it has available points to yesterday after I did the Restore.

Only the .bak has a recent previous version at 3/2/15, but it looks that file only keeps closed tabs.

I'll try those programs and see if they find more restore points than Windows...

It is probably more about finding a copy of the sessionstore.js file.

System Restore Explorer has found a recovery.js 3/2, a recovery.bak 3/2 and a previous.js 1/31. ALL under sessionstore-backups. No sessionstore.js... only the old -1, -2, -3.js and .bak shortcuts! Also a upgrade.js-20150122214805 1/31.

Would that help??

I can find how to download the other one.

Please back up all these sessionstore related files somewhere safe where Firefox won't replace them.

Recent versions of Firefox no longer use sessionstore.bak. Instead it uses the recovery.js and previous.js that you found in the sessionstore-backup folder.

When you exit Firefox, recovery.js is copied to the main level of the profile folder and renamed sessionstore.js. When Firefox starts, it reads and deletes sessionstore.js.

In order to substitute a different session file for sessionstore.js, exit Firefox, rename/remove sessionstore.js, then copy the other file into the folder and rename it to sessionstore.js. Firefox should read that file at startup, and you can try Restore Previous Session from the History menu.

By the way, the page for viewing a previous session is called about:sessionrestore and not about:sessionstore.js. For future reference, the about:about page has links to many of the about pages.

A quick way to inspect a sessionstore.js file is opening the file in a tab and evaluate this JavaScript code.

eval("ss = "+document.body.innerHTML.replace("<pre>","").replace("</pre>",""));
sd='';
for (var i = 0; i < ss.windows[0].tabs.length; i++) {
 var ent = ss.windows[0].tabs[i].entries;
 var last = ent[ent.length-1];
 sd+="<a href="+last.url+">"+last.url+"</a><br />";
}
document.body.innerHTML=sd;

What folder shall I copy it to? I do not have any sesionstore.js in the Profile Folder, only a pointer and a -1.js, -2.js and -3.js.

I deleted them all and renamed the recovery.js as you said. Oped Firefox and it didn't work!

A very strange thing happened: when i opened Firefox and called the About:sessionrestore, the sessionstore.js I had just renamed went from 2,265KB to 1KB !!??

The file is not opening, neither before or after.

Hello!!!

Did you try to open the file in a Firefox tab for inspection?

The above posted code for the Web Console should show links in the file if the file isn't corrupted to see if it would work to use the file to restore the session saved in it.

The sessionstore.js should be copied to the main Firefox profile folder. If the file name differs then rename the file to sessionstore.js.

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox