I apologize that this is in English instead of German:

Session Restore Failed?

Is the problem that Firefox did not re-open the actual tabs that were open before the update -- instead the tabs are blank ("New Tab")?

We might be able to find your tabs. Please back up your session history files. Here's how:

You can 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 "Open Folder" button.

In your profile folder, scroll down and double-click into the sessionstore-backups folder.

Save all files here to a safe location, such as your Documents folder.

The kinds of files you may find among your sessionstore files are:

• 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) (in earlier versions, this file was called recovery.js)
• recovery.baklz4: a backup copy of recovery.js (earlier recovery.bak)
• previous.jsonlz4: the windows and tabs in your last Firefox session (earlier previous.js)
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update (earlier upgrade.js-build_id)

Note: By default, Windows hides the .js extension. To ensure that you are looking at the files I mentioned, you may want to turn off that feature. This article has the steps: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

You can check the contents of a session history file using a tool on my website: https://www.jeffersonscher.com/res/scrounger.html

You drag a file from Windows Explorer and drop it on the box, then click the "Scrounge URLs" button to see whether it has the missing information. You can save the list as an HTML document and use the links that way, or we can try to explain how to switch Firefox from using your current (broken) session to one of the older ones.

Is this about the Windows Taskbar showing icons that you need to hover to see a preview instead of seeing a list?

@jscher2000 Thank You for Your answer. Unfortunately it doesn't quite cover my problem. Maybe I haven't expressed myself precisely enough. I add: My firefox doesn't show any tab at all, no restored ones, no new ones, no blank ones. On top of the screen/Window there is the menue bar, underneath the bookmark bar. And underneath the bookmark bar there used to be a bar with the tabs of my opened sites. This has vanished completely. Instead of I can either use the arrow down button, to see a list of my opened sites or hover over icons in windows task bar at the bottom of the screen. Both possibilities are not as comfortable as my former tabs. Therefore I would like to get those back.

@cor-el Thank You also. Yes exactly. When hovering over the icons in Windows task bar I can see previews of the opened sites. But I would prefer to see my tabs as before the update. Remainder see my obove answer to jscher2000.

Would you please check this setting :

Type in the address bar 'about:preferences' and press Enter. In the General panel, under 'Startup' => ' When Firefox starts' make sure that 'Show your windows and tabs from last time' is checked.

See : https://support.mozilla.org/en-US/kb/restore-previous-session#w_when-youve-set-firefox-to-show-your-windows-and-tabs-from-last-time

If that doesn't do the trick, you could give this a try :

Type in the address bar about:config (press Enter0 (promise to be careful, if asked) Type and look for the preference : browser.startup.page and set its value to 3

Also see : http://kb.mozillazine.org/Browser.sessionstore.enabled

Do you have any tab related extensions?

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

lapfuchs said

On top of the screen/Window there is the menue bar, underneath the bookmark bar. And underneath the bookmark bar there used to be a bar with the tabs of my opened sites. This has vanished completely.

Hmm, the normal sequence is:

• Title bar (optional)
• Menu bar (optional)
• Tabs bar
• Main "navigation" toolbar
• Bookmarks Toolbar (optional)

It sounds as though your toolbar area layout was customized using either an extension or a custom style rule (for example, in a userChrome.css file). You may need to disable to remove those.

Thanks to everybody. Solved the "problem" more or less by chance myself. The solution was VIEW-TOOLBAR-ADAPT-RESTORE STANDARD. And there were the tabs again. Sorry for having bothered You.