Hi master5754, if the Restore Previous Session menu item is grayed or missing, it can mean either: (A) Firefox already restored your session, or (B) Firefox didn't find a previous session.

For scenario (A), can you find any missing windows using any of these menus:

• "3-bar" menu button > Library > History > Recently Closed Windows

• "Library" toolbar button > History > Recently Closed Windows

• (menu bar) History > Recently Closed Windows

(The adjacent Recently Closed Tabs menu is per window, so first you need to get the window back.)

If that doesn't help...

Could you test your backed up session history files here:

https://www.jeffersonscher.com/ffu/scrounger.html

After dropping or opening a file in the page, click Scrounge to extract the URLs. You can save the HTML formatted list as a backup in case the file is never able to be restored.

Do any of your files have the correct list?

In case you use "Clear history when Firefox closes".

• do not clear the Browsing History

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings
• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

For Scenario A - I couldn't find any missing windows only after attempting to restore initially. During the first restore it brought up blank windows. After seeing this I force quit the application and re-opened in hopes that it would ask me to restore the session but it didn't, now it shows only one blank window.

I did notice a significant difference in the file size between the old and new "recovery.baklz4" file

Not sure what you mean when you say "Do any of your files have the correct list?" - Can you be more specific?

jscher2000 said

Hi master5754, if the Restore Previous Session menu item is grayed or missing, it can mean either: (A) Firefox already restored your session, or (B) Firefox didn't find a previous session. For scenario (A), can you find any missing windows using any of these menus:

• "3-bar" menu button > Library > History > Recently Closed Windows

• "Library" toolbar button > History > Recently Closed Windows

• (menu bar) History > Recently Closed Windows

(The adjacent Recently Closed Tabs menu is per window, so first you need to get the window back.) If that doesn't help... Could you test your backed up session history files here: https://www.jeffersonscher.com/ffu/scrounger.html After dropping or opening a file in the page, click Scrounge to extract the URLs. You can save the HTML formatted list as a backup in case the file is never able to be restored. Do any of your files have the correct list?

master5754 said

Not sure what you mean when you say "Do any of your files have the correct list?" - Can you be more specific?

You won't know how to answer that until you use the Scrounger tool to extract the contents of at least one of your files.

Ok, is there another way to fix this issue?

Does that mean you don't have any session history files that contain the missing tabs, and you may need to resort to an older Time Machine backup or digging around with a deleted file recovery tool?

I have all the session history files, It just takes a much much longer time to sift and sort through them all. The way I had my windows organized was built up overtime, which would enable me to find what I was looking for much easier then relying on the history files. It's just difficult for me to believe that this could happen when I've never had such an issue over the past year(s). I feel as though my downloading of a few add-ons contributed to this problem since that is the only thing I've recently done that has been out of my normal utilization of Mozilla. Even now when I try to download an add-on, it wont register. Jscher2000, do you work for Mozilla?

Hello master5754,

Would you please take a look at this (the fact that the OP there is on Linux doesn't matter) :

https://askubuntu.com/questions/1085760/mozilla-firefox-quantum-63-0-restore-previous-session-greyed-out/1086697

Any chance that it's as simple for you as well ?

I think my meaning got lost in translation. When I refer to Session History files, I mean these:

• sessionstore.jsonlz4: the windows and tabs in your last Firefox session after a normal shutdown
• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update

You mentioned that you backed up your Session History files from the sessionstore-backups folder. You also mentioned:

master5754 said

I did notice a significant difference in the file size between the old and new "recovery.baklz4" file

So I suggested extracting a list of the tabs/windows in that and possibly other files using

https://www.jeffersonscher.com/ffu/scrounger.html

to see which one would be the best candidate for restoration.

To try swapping in an older session history file in place of your latest one, the standard "manual swap" method is as follows (assuming Firefox is still running):

(1) From inside Firefox, 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 "Show in Finder" button. This should launch a Finder window listing the various files and folders in your profile.

(2) Leaving that window open, switch back to Firefox and Quit, either:

• "3-bar" menu button > "power" button
• (menu bar) Firefox > Quit Firefox

Pause for 15 seconds to allow Firefox to finish its cleanup.

(3) Once Firefox has stopped updating things

(A) Rename the sessionstore-backups folder to sesionstore-backupsOLD

(B) Rename sessionstore.jsonlz4 to sessionstoreOLD.jsonlz4

If you see an older sessionstore.js or sessionstore.bak file, move it somewhere else or delete it.

(4) Copy in the other file you want to restore, and rename it with the name appropriate for its format:

• Compressed file such as recovery.jsonlz4 => sessionstore.jsonlz4
• Uncompressed file such as recovery.js => sessionstore.js

(5) Start Firefox and it should read the swapped in sessionstore.x file and restore whatever was in the substitute file; if you do not have Firefox set to restore your previous windows and tabs automatically, use History > Restore Previous Session

Any luck?

No luck, definitely looks like this could have been resolved much easier. Don't see why Mozilla doesn't have tech support assisting with this situation since it seems to be a common problem among others within the community.

master5754 said

No luck, definitely looks like this could have been resolved much easier. Don't see why Mozilla doesn't have tech support assisting with this situation since it seems to be a common problem among others within the community.

This is the tech support you're talking to. Volunteers mostly.

When you say "No luck", where did your luck run out?

(A) Do any of the files contain the set of windows and tabs you want to restore, which you confirmed by extracting the list using the Scrounger tool?

Which one(s)?

(B) If you have a useful file, did you try to "swap" it in?

What happened?

A: No B: Yes

The sessionrestore page continues to load blank, therefore leaving me with no option to restore the previous session.

There also now seems to be a problem with the sync of the mozilla account, and inability to install add-ons. Dunno whats going on but it seems as though the normal functionality of FF is very much out of order.

master5754 said

A: No

If you do not have a file containing the old tabs, then it sounds as though the backup you made of sessionstore-backups was too late. Two other possible sources of session history files would be:

(A) Deleted File Recovery

At least one user reported being able to dig up additional copies of recovery.jsonlz4, recovery.baklz4, and previous.jsonlz4 using Recuva, a Windows tool. I don't know whether there are similar tools for Mac.

(B) A Time Machine backup

When you are in Finder viewing the sessionstore-backups folder, I think there is a way to check whether Time Machine has backup copies of files for that folder. However, I don't know the details.

Would you please check these settings :

Options => Privacy & Security => under "History" => choose "Use custom settings for history" and make sure that both "Always use private browsing mode" and "Clear history when Firefox closes" are unchecked.

@McCoy Those settings are unchecked.

@jscher2000 What is the file name are you referring to that contains the old tabs. I didn't see a file named "previous.jsonlz4"

The method used was similar to what you described in an earlier post. I typed about:session in the address bar in FF and it brought me to a page where it gave me an option to open the storage files in finder. I didn't use any 3rd party apps to locate the files.

One thing I have noticed is that now when I open FF it doesn't ask me to restore previous session, it automatically opens the tabs I had open in previous session.

master5754 said

@jscher2000 What is the file name are you referring to that contains the old tabs. I didn't see a file named "previous.jsonlz4"

Yes, your original question said:

master5754 said

I made a copy of the sessionstore-backups folder, then closed firefox, replaced the new sessionstore-backups folder, then restarted firefox and problem continued to persist.

The kinds of files you can find in that copy are:

jscher2000 said

• sessionstore.jsonlz4: the windows and tabs in your last Firefox session after a normal shutdown
• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update

Doesn't seem to want to work out. I've just started a new session and trying to rebuild the long and tedious way. I kept the files just in case I come across something or someone that might be able to contribute a solution to the problem. I appreciate your attempts to do so.