Hello, Firefox Sync is not a backup or migration service. It is only for synchronising browser data between two or more devices running Firefox at the same time. If you sync your data to Firefox Sync and then wipe your machine then there is a chance that you will not be able to recover your data. If you are moving from one machine (or OS) to another the best way to do it is by following the steps here: [[Back up and restore information in Firefox profiles]]. Is your Windows installation gone completely? If you can still boot into Windows then I suggest following the steps in the article above to backup your Profile. Copy the backup to your Linux machine and restore there. If you cannot boot into Windows then there may be a problem. If you have your [https://support.mozilla.org/en-US/kb/how-do-i-manage-my-firefox-sync-account?esab=a&s=recovery+key&r=1&as=s#w_where-can-i-find-my-recovery-key recovery key] then you can use that to pull down the information from Sync and get it onto your new machine. If you do not have your recovery key then I don't think it will be possible to restore your data using Firefox Sync. You may be able to recover / undelete your profile folder or your [[Restore bookmarks from backup or move them to another computer|automatic bookmark backups]] using one of the tools [http://www.linuxforu.com/2011/09/recover-deleted-files-in-linux/ here]. I hope this helps. Also see here for another similar question - https://support.mozilla.org/en-US/questions/973460?esab=a&s=lost+sync+&r=4&as=s

Cheers! I don't have Windows at all right now, all partitions were deleted, I saved the key, I'll try it in a moment.

Ok great. If you have the key then you may be all right. Let me know if you manage to recover the data. Good luck :)