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

Check all the settings.

Make sure you are not in Private Browser.

You can check browser.sessionstore.* prefs including browser.sessionstore.resume_from_crash on the about:config page and reset browser.sessionstore prefs that are user set (bold) via the right-click context menu to the default value to make sure that Session Restore is enabled and working properly.

• http://kb.mozillazine.org/Session_Restore
• https://support.mozilla.org/kb/restore-previous-session
• http://kb.mozillazine.org/browser.sessionstore.resume_from_crash

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Hello FredMcD abd cor-el,

Thank you for the responses.

1. I checked and I am not in Private Browsing 2. I have reset all prefs to "default" and all the options under "History" are still greyed out.

I cannot undo any closed tab, either from the History tab or from my add-ons. None of them will work.

So what's next?

I have been a big supporter for Firefox for years (since its first version). But I have to say, the last few updates have really made Firefox worse. I understand that Mozilla can do nothing about the "add-ons" problems, but as far as the normal performance of Firefox in general, it's getting worse.

I have to continuously end the process of the "plug-in containers" because of the "flash" issues (which has been ongoing for years). I understand, this is another issue Mozilla can't do much about it, but before version 30, I usually only need to end the process, maybe once or twice a day. But now, almost once every hour!

Thank you.

Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Hello cor-el,

I created a new profile and the 'Recently Closed Tabs' under History worked!

I am ready to transfer files from my old profiles into the new one. But how do I know which files are corrupted? I read the KB link you sent and it seems I would have to transfer some files and then test and then do another batch, right?

I also have started FF with add-ons disabled, everything under History is still greyed out. So it seems that my add-ons are not the ones that causing the issue. I did start FF in Safe Mode and the Recent Closed Tabs worked.

Since updated to the last three versions, I have the following issues:

1. Cannot log into my Chase accounts (other bank accounts are fine). I have to use IE Tabs to do so. 2. "sessionstore" does not work, and cannot undo closed tabs. 3. The latest one is I cannot use File / Exit to close FF. I have to use the "x" on the corner to close it instead. 4. Everything else seems fine. My history are saved and my homepages are saved when restarted.

Hopefully, the next update will be better.

Thank you.

You can start with some files that you really need and first rename the existing file by adding a .OLD file extension, so you can revert this (i.e. do not overwrite the existing file).

Do you have any sessionstore files in the main Firefox profile folder?

You can also try to delete the sessionstore-backups folder to remove the backups in that folder.

Hello cor-el,

The only sessionstore file I have is the .bak file, but it was dated 9/24/2014.

I'll delete the backups folder to see if that helps.

Also I noticed that in my Profile, I have some very old pref.js files, will that be the ones that are causing my problems? Should I delete them?

I have attached a jpg for you to look at.

Thank you.

It may be best to copy only the bookmarks, history, passwords, and add-ons. If you try to move a settings file, it may be corrupted.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences

Hello FredMcD,

Thank you for your response. Yes, I do agree. However, since there are so many folders/files in my Profile, it's kind of difficult to distinguish which ones are which sometimes.

I backup my Profile once a month. I went to copy my November profile into my new profile, but FF won't start. It kept asking me for the Master Password, which I have entered at least 15 times! So I gave up.

I used to use FEBE but disabled it sometime ago because it wasn't compatible with the FF version I was using. I still have it in my add-on list (but disabled), maybe I'll give it a try again.

I'll try to find some time to create another profile and copy those files that I think are not setting files. I'll post my update later here.

If anyone of you have any ideas for the time being, please feel free to let me know.

I am still kind of confused why do I have so many pref.js files in my Profile.

Thank you.

OK, Here's my latest:

I created a new profile, copy ALL folders and files from my old profile into this one. Then I delete all the pref.js files except the latest one. Start FF with the new profile, guess what, everything is back to what is supposed to be.

1. Restore Previous Session and Recently Closed Tabs are both now working under the History tab. 2. I can log into all of my Chase accounts, without using IE Tab. 3. File and Exit is working again.

So it seems that all those old pref.js files were the culprits here.

Thanks to FredMcD and cor-el for all of your kind assistance.

FEBE has not been any problem for me, except for a few things once in a while. The writers keep up and when a problem comes out, so does an update. I use FEBE to automatically back up my profile every day. I keep 30+ days of backups, just in case.

If you decide to restore it, I highly recommend it, get the full install.

my solution: close ff. open prefs.js in a text editor find "user_pref("browser.migration.version", xx);" and delete it(xx is a number) save and start ff, then everything is ok.

my solution: close ff. open prefs.js in a text editor find "user_pref("browser.migration.version", xx);" and delete it(xx is a number) save and start ff, then everything is ok.