What is the sync key? What is it used for? In a worst-case scenario, what if you lose it?
I recently came across the key and don't want to lose it, but have never needed it, either. See also:
Hi. Before to re-install Windows, I saved my Firefox Sync Key. After windows installation, I can't to access my firefox sync account to get my bookmarks! It says: unknown account, register! But I have a KEY, I need my bookmarks back!
Help me, please, to recovery my bookmarks back! Thanks.
https://support.mozilla.org/en-US/questions/1040248
I've never run into that.