Hello,

Please try refreshing both Firefox to return it in default state. Then try syncing again.

The Refresh feature (called "Reset" in older Firefox versions) can fix many issues by restoring Firefox to its factory default state while saving your bookmarks, history, passwords, cookies, and other essential information.

Note: When you use this feature, you will lose any extensions, toolbar customizations, and some preferences. See the Refresh Firefox - reset add-ons and settings article for more information.

To Refresh Firefox:

1. Open the Troubleshooting Information page using one of these methods:
   • Click the menu button , click help and select Troubleshooting Information. A new tab containing your troubleshooting information should open.
   • If you're unable to access the Help menu, type about:support in your address bar to bring up the Troubleshooting Information page.
2. At the top right corner of the page, you should see a button that says "Refresh Firefox" ("Reset Firefox" in older Firefox versions). Click on it.
3. Firefox will close. After the refresh process is completed, Firefox will show a window with the information that is imported.
4. Click Finish and Firefox will reopen.

Did this fix the problem? Please report back to us!

Thank you.

You can check on the about:sync-log page if there is a Sync error log available.

You can open about: pages via the location/address bar.

You might have to turn on logs in order to capture any errors there:

• How do I turn on sync logs:

1. Open about:config and turn on: services.sync.log.appender.file.logOnSuccess and services.sync.log.logger.engine.bookmarks
2. Restart Firefox and look at: about:sync-log
3. Logs and error messages will be located here

Please also use pastebin.mozilla.org for sharring any errors that relate to this issue.

Thank you.

Once you are done with testing then best is to reset services.sync.log.appender.file.logOnSuccess to false to avoid creating a lot of unnecessary log files.