Hello,

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you for contacting Firefox Support!

Make sure that you allow cookies for the accounts.firefox.com domain.

You can check the about:sync-log page via the location/address bar to see if there are recent error logs available.

In case of issues with Sync you can try this:

Disconnect from Sync and Reconnect to Sync again.

You can disconnect from Sync by clicking the e-mail address in the "3-bar" Firefox menu button drop-down list or go to "Options/Preferences > Sync".

Delete the signedInUser.json file in the Firefox profile folder and delete the Weave folder (Sync was formerly named Weave).

Remove an existing chrome://FirefoxAccounts entry in the Firefox Password Manager. If that isn't enough then delete the prefs.js files to reset all prefs and maybe also delete the compatibility.ini file to reinitialize the profile.

Delete and re-create the Firefox account or change the Sync password.

Note that changing the Sync password will wipe all data stored on the Sync server.

Can you log in to the Sync account via this page?

• https://accounts.firefox.com/settings

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

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

Deleting and reinstalling Firefox didn't help.

Yes. I am able to log into the Sync account via https://accounts.firefox.com/settings. From the settings page, I deleted the account and created a new account with a different password.

That did not solve the problem. I still cannot log into sync via the sync tab on any of my PCs. I get the same 'working' red bar and a swirly in the sign in box. I can still log into the newly created account via https://accounts.firefox.com/settings

Thanks.

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

hi, unfortunately this is currently a known issue in firefox 50 when you have set the browser to run in permanent private browsing mode ("never remember history" in the options > privacy panel). firefox developers are working to get this fixed in upcoming versions again...

Settings for privacy, browsing history and do-not-track

Thanks for all of the replies. I finally managed to get it fixed by refreshing Firefox in the Troubleshooting Information section of the help menu.