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Hello, I have a big problem with Firefox: Session Manager & Undo Closed Tab addons are not working, Sync Is not working. History is working. How to fix this?


Firefox remembers history but doesn't remember closed tabs, sessions. It happened after updating Fox to v. 19.0.2 on one computer.

In Firefox Options is set Use Custom Settings For History, everything is checked except Always Use Private Browsing Mode. So I am not in private browsing.

When I press on Undo Closed Button nothing happens & in session manager Save Session Button is greyed out. I've tried installing other add-ons that can remember tabs. tried to disable/reinstall these 2 add-ons. Did't help. On my 2nd computer I have same add-ons, same settings and they are working normally. on 3rd computer undo closed tabs works also. How to fix this? I decided to ask before doing Firefox Reset...


Sync is a separate problem. It works, but quite often it logs me out of Sync account. Then I can log in only using long recovery key and password (choosing option I don't have device with me because it does not accept keys for pairing device.)

Thanks for reading.

Chosen solution

In case you are using "Clear history when Firefox closes":

  • do not clear Browsing History

Note that clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.

Read this answer in context 47

Additional System Details

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10738 solutions 96600 answers

Chosen Solution

In case you are using "Clear history when Firefox closes":

  • do not clear Browsing History

Note that clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.

Question owner

I have exactly the same settings in Options (in both computers) for history, these 2 add-ons and all other stuff in Options. The only difference is that on 1 pc sessions can be saved and closed tabs can be reopened, on other main pc they stopped to work. + no any other add-on that does similar things works on this pc.

It is also interesting that I can reopen closed visited sites from History Panel, but not by pressing the Button. For now I only manually bookmark links to a temporary folder.

Recently (some 2 month ago) I pressed x and Firefox closed all tabs without saving them without displaying save & quit pop up.

so I changed 4 settings in about.config

browser.tabs.warn on close true browser.warn on quit true browser.warn on restart true browser.show.quit warning true

but the problem with sessions appeared only 1 week ago.

So I guess the problem is not with the History settings or other settings. Seems that something responsible for button or for storing info about tabs/sessions got corrupted.  :(

Question owner

Solved It! It happened that not everything was checked to Sync only Bookmarks. I checked everything in both Mozillas. After restart now it works perfectly as before :))))))))))) !

Thanks for advice not to clear history. Saved passwords were checked to be cleared after close. maybe that is why sync was logging me out.

tecsi 0 solutions 2 answers

Can no longer load previous sessions with Session Manager. A rather huge issue as you lose your entire browsing context