dede198807 said

After updating Firefox to version 42 I can´t see the tabs that are open. Wenn I open a new tab I see the homepage, but there isn´t a new tab on the tab display at the top of the firefox window.

Update: When I open a new Firefox Window, Tabs working normal.

Hi, first try restarting Firefox - 3-bar menu > Exit Firefox in bottom right corner.

If that doesn't work, try clicking on Restore Defaults as shown in Customize Firefox controls, buttons and toolbars.

If that doesn't work, try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB

Make sure that you do not run Firefox in Full Screen mode (press F11 or Fn + F11 to toggle; Mac: Command+Shift+F).

• https://support.mozilla.org/kb/how-to-use-full-screen

When you are in Full Screen mode, hover the mouse to the top of the screen to make the Navigation Toolbar and Tab bar appear. You can use one of these to leave Full Screen mode:

• click the Maximize button (top right corner of the Navigation Toolbar) to leave Full Screen mode
• click the Full Screen button in the "3-bar" menu button drop-down list
• right-click empty space on a toolbar and choose "Exit Full Screen Mode"
• press the F11 key

Try to rename (or delete) the xulstore.json file in the Firefox profile folder. You can check for problems with the sessionstore.js file in the Firefox profile folder that stores session data. When sessionstore.js is deleted you lose App Tabs and Tab Groups and open tabs and you will have to recreate them, so if necessary make a note or bookmark them.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox