Firefox 29 “Sync” nightmare

The — as I later found out — completely revamped “Sync” feature in Firefox 29 caused me a lot of grief yesterday, and I wasted more than 3 hours due to it. :-(

The issue started after I had to set the system time back on one of my Macs which I hadn’t used for a couple of weeks, so the Firefox data on that machine was outdated and not in-sync with the other machines synced to the same Firefox Sync account. Not sure whether setting the date back was the root cause, but anyway… I suddenly noticed that I had old passwords on another machine, too. Obviously it had received them via Firefox “Sync” from said Mac.

So, what to do?

I first cleared the data stored in my Firefox Sync account by logging on to the old account management (, to make sure that the outdated passwords do not propagate to more machines.

I then disassociated the machines that had already received the outdated passwords from Firefox Sync.

Afterwards I wanted to add the device back the same way I did when adding a new machine in the past. But it didn’t work as it used to work. No way I could display the sync code I needed to enter on the “master” machine. :-(

Instead I got some unfamiliar screen which I had never seen before that would not accept my existing Firefox Sync account credentials:


Firefox Sync "Sign in"

After I had wasted a lot of time without finding a solution, I turned for help to the Mozilla #firefox IRC channel, since I wanted interactive and quick help.

I was soon told that Firefox Sync had been completely revamped in Firefox 29. Bummer!

Did I really miss this important announcement??? (Yes, I did read the release notes when upgrading to Firefox 29, at least I glanced thru them!) Or was this info simply not present or well hidden in the release notes?!

Anyway, here is how to migrate to the new Firefox Sync service.


I hope that this short article saves people some griefs with this (at least for me) indispensible feature.

Leave a Reply

Your email address will not be published. Required fields are marked *