Hi ! Maybe if you try to disconnect from the account and try to connect again. I had this problem in an earlier version of FF. It disappeared when i did something like this above.

Thanks nofeartompa.

Unfortunately I've already tried that.

I've also seen other comments about cookies being required - but cookies are allowed and are being created for accounts.firefox.com, so that seems fine.

I have also tried a full profile reset.

Hmm seeems odd. So do you know what should be syncing ? Either if you create another user on your computer, log in to that user account and then try. Also if you happend to have another computer to try on so you know that it is working before you loose all your hair in finding the problem on this one :-) .

What I'm looking to see synced: History, bookmarks, extensions, open tabs, etc.

I have now tried creating a new user. This eventually fails at the same point. After getting Mozilla to send a verification email the firefox window displays a message in orange "Invalid Request Signature" (attached screenshot - email address removed). On receiving the message and clicking the link, I see a similar windows saying my account has been verified and I'm okay to start syncing - but nothing happens same "is not verified" and other symptoms as before.

Going back to the "Unexpected error Missing authentication" message when logging into accounts.firefox.com on all browsers. Could there be something going wrong about proxies, etc. (corporate setups) since this all works fine from home? What would I ask them to fix?

Aaaah Ok. Yes of course it can be some protocol and port that Corporate IT maybe have closed/blocked. I will check and get back to you but it should only be http/https protocol and the port 80 that usually is used for surfing. //Tom

Hi Tom,

Normal web browsing is working - I can connect to most websites fine http or https. I can also view the error messages delivered from accounts.firefox.com fine.

I think it has something to do with the sync server rejecting the authentication that my corporate network has set-up.

I've attached a screenshot (company name obscured).

Hi ! Hmmm it beats me, but maybe we need to figure out how Firefox connects to your company, maybe as you say, it gets stopped at the door... I tried to look up how it connects but it's somewhat complicated......

Maybe you can get help here:

https://services.mozilla.com/status/

What does the Sync log show if you check that via the about:sync-log page?

There are 15 odd files, most 20kB one 1mB:

I'm mostly just looking for lines that mention ERROR. Not sure which lines are fine to post publicly - is the line that has email addresses, uids and sessiontokens the only one I'd need to censor? Any particular lines you are looking for? Or a particular procedure to follow to generate the lines you want?

I have closed firefox, delinked and relinked sync and placed the log on paste bin here: http://pastebin.com/Nf8LDN5n

An error repeated in most files: 1413432422654 FirefoxAccounts DEBUG entering pollEmailStatus: start 1413432424027 FirefoxAccounts ERROR error GETing /recovery_email/status: {"code":401,"errno":109,"error":"Unauthorized","message":"Missing authentication","info":"https://github.com/mozilla/fxa-auth-server/blob/master/docs/api.md#response-format"} 1413432424081 FirefoxAccounts ERROR error POSTing /recovery_email/resend_code: {"code":401,"errno":109,"error":"Unauthorized","message":"Missing authentication","info":"https://github.com/mozilla/fxa-auth-server/blob/master/docs/api.md#response-format"

There is one error log file that is a megabyte (where most of the files are 20kB), it mostly has the following lines repeated (also seen in other files): 1413857031238 Sync.Tracker.History DEBUG Saving changed IDs to history 1413857032499 Sync.SyncScheduler DEBUG Global Score threshold hit, triggering sync. 1413857032500 Sync.Service DEBUG User-Agent: Firefox/33.0 FxSync/1.35.0.20141011015303. 1413857032500 Sync.Service INFO Starting sync at 2014-10-21 10:03:52 1413857032500 Sync.Service DEBUG In sync: should login. 1413857032500 Sync.Service DEBUG Exception: Could not acquire lock. Label: "service.js: login". No traceback available 1413857032500 Sync.Service INFO Cannot start sync: already syncing? 1413857032500 Sync.Service DEBUG Not syncing: login returned false.