hello, you can go to firefox options > sync panel. click on set up firefox sync > i have an account > i don't have the device with me where you can enter your existing credentials.

if this worked and you could import your data successfully, please migrate to the new sync afterwards: Sync your Firefox bookmarks, history, passwords and more

First - I trust that you were using Firefox 28 (or older) on your "last device".

2nd, do have another connected device on that Sync Account where you can get use Pair a Device?

Or, do you have all three of these? Email address for your Sync account. The Password for that account. The Sync Key for your account (aka Recovery Key).

If so, see this: https://support.mozilla.com/en-US/kb/add-a-device-to-firefox-sync

Hi!

Thanks a million for your fast reply! I followed it through, but in the end I either need another paired device, which I have not, or to create a new key which results in erasing all stored data :-(

The frameshot attached to this post explains, that the data is encrypted and only paired devices have the key...

Now I know :-/

Again, thanks for your effort, what a pity when both paired clients "die" within the same couple of days. But with the new sync this problem will be history.

BR, oaito

I deleted your screenshot because you don't want people to know your recovery key ;)

Make sure you update to Firefox 36.0.1 and then update to the new sync Sync your Firefox bookmarks, history, passwords and more