firefox.com1 said

... Surely the good developers of this facility have written down how it works and how it is supposed to be set up - eg - what is retained on FF servers, - how can parts (eg passwords) be removed from FF servers, or from one of the devices? - what is overwritten in the synced profiles - what happens to conflicting settings - what determines which setting will prevail in the case of a conflict - how to remove unwanted tabs/settings which have been synced - what determines which bookmarks/passwords/tabs/addons end up where? - what determines which addon settings prevail if there is a conflict? - are addons settings even synced? - does it change tabs order? If so, what determines the order? -Does it ADD tabs to both devices, does it REMOVE tabs? - does it retain containers? - how do you update a sync and ensure up to date data is transferred? - on a device, eg iphone, what is the procedure to switch between different synced profiles without getting them mooshed up together? - etc etc. Can someone please put a link to those instructions and specs here? With a link in it for users to ask questions which will be answered in the same page by the designers, so we don't have to trawl (often without success) through pages of guesswork and unworkable workarounds? Many thanks

I have been requesting that information (in the Contributors Fora here) to be properly documented in the Knowledge Base here for many years to no avail. And all I get is to start a KB article and wait for it to be edited by other contributors; problem for me is that I have no real use for Sync with no mobile devices and a solitary desktop computer now. I can only use Sync to synchronize multiple Profiles on the same PC, but it is a far sight from really using Sync as it was intended.

To answer some of your questions ....

1. The "designers" of Sync rarely grace us with their presence here at SUMO (SUpport.Mozilla.Org), especially on weekends. Occasionally one Sync developer has answered questions here but with no regularity.

2. As far as what is retained on Sync servers; whatever types of data the user selects (bookmarks, passwords, etc) will get saved. When a new device is added to the Sync account (Firefox Account = FxA) the data already on the Sync server will get sent to that new device AND the data on that new device will get sent to the server; but that doesn't happen instantaneously and sometimes it may take days for the Sync process to be fully completed - but that depends upon the amount of data involved. Also the overall load on the Sync server the users account is sitting on is a factor.

3. There is no user control over how the Sync server handles bookmarks; they all get merged initially and as time goes by the server will attempt to make sense of all the merged bookmark data. But the server won't try to merge the same bookmarks that are in differently named folders that originated on different devices or Profiles; and if or when the user attempts to "fix" what they see as "wrong" by manually re-arranging bookmarks ordering the user is faced with big issues - DO NOT attempt manually moving too many bookmarks around while the device is connected to the Sync server, that will just make the situation worse.

As far as Firefox for iOS & Firefox for Android are concerned, the Sync server handles their bookmarks separately from bookmarks on Desktop / Laptop devices. I have no idea HOW different the "Firefox for ..." works with bookmarks, other than the amount of problem threads (over the last 3 years) that I have weighed in on with Mobile questions once the process goes "head over heels" and a users bookmarks get royally screwed up, and everything that user tried to do to fix it didn't work.

4. Add-ons settings getting synchronized - that can depend upon the add-on and how the developer of a particular add-on set-up their add-on. In the past many add-ons have had settings hidden in about:config and no posted "clues" about what each "hidden preference" might control; but that was with the old Legacy extensions (before Fx 57) - since then I stopped "playing with Sync" to expand my knowledge of how Sync works.

Bottom line is that I participated in the creation / development of Sync when it was called Weave in the Fx 3.5 / 3.6 as an optional add-on; when Fx 4.0 came out with Sync being built-in I had to stop using Sync due to lack of backward compatibility with Weave on my old ASUS eeePC Netbook. By the time I came up with a newer Linux distro that would handle Fx 4.0, I had given up on using Sync.

Thanks so much for your efforts,

1. that's half the knowledge base page DONE... maybe if one of you please just opened a page with what you have posted here, it could be added to?

2. Um are you really telling me mozilla added sync without anyone explaining to them what it does, how it works, and how it is to be operated? Come on... pull the other one... (though it would explain some of the disasters with updates...) Can someone just put THAT up as the rest of the KB page? A partial KB page is better than none.

3. How can firefox boast about privacy and security if they can't even explain what sync does and does not do???

Would be especially helpful to have warnings such as

"your bookmarks will be screwed up on ios [doTHIS-eg export/import bookmarks separately?] instead ...

"NEVER sync password because they will be KEPT ON THE SERVER AND YOU CAN NEVER DELETE THEM. [suggest alternative way to transfer them!]

I'm thanking my good sense that I didn't sync my passwords and bookmarks before I ascertained what that does. Those who have, should be really concerned, in fact FURIOUS.