Hello ,

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall 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 http://www.mozilla.org and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
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.

There have been problems reported with Sync lately and you might be experiencing them.

• bug 1045691 - Firefox sync fails with "unknown error" graybar message and 502s

Please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html

Hi Ponnifer,

You don't mention the version of FF you're using.

Sourjobraato mentions downloading the latest version of FF for a clean reinstall, which I agree is usually best.

However, if you rely on a master password to protect your sync data you may want to avoid newer versions of FF (version 29.0 to current), because you cannot sync passwords and use a master password simultaneously. https://bugzilla.mozilla.org/show_bug.cgi?id=995268

I'll leave it to those more informed to discuss the relative benefits of unprotected passwords vs. other security improvements newer version of FF may provide.

Thank you.

Sorry, it's Firefox 31 with no master password. I will try to do a clean install and see whether it works.

But here is my latest error log file:

1407197431088 Sync.Status DEBUG Status.service: success.status_ok => success.status_ok 1407197431088 Sync.Status DEBUG Status.service: success.status_ok => success.status_ok 1407197432085 Sync.Tracker.Addons DEBUG Saving changed IDs to addons 1407197549157 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197554762 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197559314 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197572264 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197584126 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197604023 Sync.SyncScheduler DEBUG Global Score threshold hit, triggering sync. 1407197604023 Sync.Service DEBUG User-Agent: Firefox/31.0 FxSync/1.33.0.20140716183446. 1407197604023 Sync.Service INFO Starting sync at 2014-08-05 08:13:24 1407197604024 Sync.SyncScheduler DEBUG Clearing sync triggers and the global score. 1407197604024 Sync.Status INFO Resetting Status. 1407197604024 Sync.Status DEBUG Status.service: success.status_ok => success.status_ok 1407197604025 Sync.BrowserIDManager DEBUG _ensureValidToken already has one 1407197612629 Sync.SyncScheduler DEBUG Next sync in 600000 ms. 1407197613556 Sync.Tracker.Forms DEBUG Saving changed IDs to forms 1407197613893 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197630337 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197639729 Sync.Status DEBUG Status.service: success.status_ok => success.status_ok 1407197640952 Sync.ErrorHandler DEBUG Beginning user-triggered sync. 1407197640953 Sync.Service DEBUG User-Agent: Firefox/31.0 FxSync/1.33.0.20140716183446. 1407197640953 Sync.Service INFO Starting sync at 2014-08-05 08:14:00 1407197640953 Sync.Service DEBUG Exception: Could not acquire lock. Label: "service.js: sync". No traceback available 1407197640953 Sync.Service INFO Cannot start sync: already syncing? 1407197647483 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197665566 Sync.Tracker.History DEBUG Saving changed IDs to history 1407197696316 Sync.Resource DEBUG mesg: GET fail 502 https://sync-40-us-west-2.sync.services.mozilla.com/1.5/1825221/info/collections 1407197696317 Sync.Resource DEBUG GET fail 502 https://sync-40-us-west-2.sync.services.mozilla.com/1.5/1825221/info/collections 1407197696318 Sync.SyncScheduler DEBUG Starting client-initiated backoff. Next sync in 1131640 ms. 1407197696318 Sync.SyncScheduler DEBUG Next sync in 1131640 ms.