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Firefox crashes; restore session unretrievable?

  • 10 replies
  • 28 have this problem
  • 9031 views
  • Last reply by cor-el

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Hi. The other day my laptop ran out of power. I had my one, "main" firefox window up and running, and was just preparing to close the window and shut down the computer... but before I could exit (so firefox could save my tabs) it shut off.

The next time I opened firefox, expecting it to have recovered my session (and my tab groups!!) as it usually does, I didn't even get the restore window (about:sessionrestore) ... just the old homepage. All of my tab groups disappeared as well, and I thought... "this doesn't look good."

Searching around all afternoon on a public forum or two, I found information on the session.bak file - so I searched my computer for it, and found it.

NOW... when I open this file...(in mozilla firefox) I get a pile of HTML on a page --- and have no clue what to do from here. I believe that the session.bak file (dated just prior to the crash/laptop shut off) actually contains everything. I just don't know what to do from here!

Can someone help?

All Replies (10)

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Note that Windows also makes a backup of some files as part of creating an automatically Session Restore point.

You can try to restore a previous version of the sessionstore.js file.

  • Right-click: Properties > Previous Versions
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Thanks to all advice. I will give it a shot and see what I can do!

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Hi again,

So I finally got around to restoring the sessions.  I approached it at two differently each time but with similar results... (see attached photos of the tabs when I selected the restored/recovered files to "open with" firefox ).

I first when into my Appdata down to the firefox subfolders, eventually to open sessionstore.bak restore point. It ended up opening in a firefox tab what I originally opened weeks ago after just searching my computer for the sessionstore.js file... (See capture1 attached).

Second, I took the advice on TechRant and downloaded Recuva, which was sweet and worked swiftly. When I clicked to recover a sessionstore.js file dated 1.24 (about a week before the crash) it asked me to save in a new folder. I did.. and then opened the file in firefox - but I have yet to see any recovered tab groups or tabs. Only the html and other code language (see capture).

The only additional thing i'll add: before ok-ing the Recuva recovery, it asked me in a warning box "Do you want to restore to the same drive? (This can reduce the chance of a successful recovery.)"  ? I didn't totally get that - referring to my harddisk drive?

Thanks for any assistance here.

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The second screenshot shows an example where recovering the file has failed because the clusters where the file is stored have already been reused to store other (binary) data.
The first screenshot shows ACSII text and looks very promising assuming that the rest of the file looks the same and doesn't have binary data.

Weren't there any previous versions of the sessionstore.js available via Session Restore (i.e. Properties > Previous Versions)?

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There was a previous version in Window's Session Restore, but I think (unfortunately for me) I might have waited too long... it only dates back to Feb. 4, which is very close to the date of the crash, if not the date itself. (I'm not sure).

If it is the date itself, I'll try to restore the .bak or .js file, but I thought you only get one shot with Window's Session Restore... right? I already tried to restore one ( and I don't think anything happened...) before using Recuva.

Yes, first screenshot (ACSII text) should be good! My problem is: what do I do with it?

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You can make a copy of the current sessionstore.js file just to be sure and put the file from the first screenshot in the Firefox profile folder as sessionstore.js and check if Firefox accepts this file.

You can try to check the file via an online validate website:

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1st screenshot below is from Windows Session Restore now... (I didn't know which one to go for, but no of them matter - when I tried to open previous versions they've all be over-written by 3.12.14, because I tried to restore a Feb. session...)

2nd screenshoot is Recuva, still offering the 1.24.14 sessions... which is all I have to work with, and look promising. ...right?

Thanks for the guidance!
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Don't seem to be having any luck. I tried pasting the file into the JSON data field, it wouldn't accept that however; second, I tried pasting some of the ACSII text into the field - that didn't work either. And I tried pasting the URL of the mozilla tab that contains the ACSII text... nothing.

Furthermore... I realize while I did all this, that the original copy I once had updates itself - to put it plainly, I had left the session I restored into mozilla (screenshot 1) nearly a month ago, thinking that it would be preserved there. It was then, a couple weeks ago that I could read through the ACSII text and even see titles of the webpages and research links that were in my tab groups. But upon reading through the ACSII texts today, I see more recent tabs saved (from another restore point...)

Thanks for the help, I think it's time to give up the search...

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You need to paste the content of the JSON file in the text area of a JSON validator website.
Note that there is usually a size restriction of about 1 MB.

See also:

Firefox also comes with the built-in JavaScript beautifier (jsb command) as part of the Developer toolbar commands (Firefox/Tools > Web Developer) that allows to inspect JavaScript files and also works for JSON files.
Easiest is to open the file in the Scratchpad (Firefox/Tools > Web Developer) via Open file and click the Pretty Print button to format the file for inspection.

Modified by cor-el