Add-on sync only sync the "official version" on AMO, ignore what users actually install. This should be fixed. STR: 1. Original profile with non-standard version on AMO, like Firebug1.9a4, Tab Utilities 1.2pre17, then sync to server. 2. Create a fresh profile, then set up sync, the add-on sync download will be Firebug 1.8.4, Tab Utilities 1.1.2 The attachment is sync log of the fresh profile in Step 2.
As it is currently implemented, add-on sync only synchronizes extensions and themes available from addons.mozilla.org. Furthermore, and relevant to this bug, it only uses the add-on ID as a synchronization "key." When it synchronizes an add-on, the client effectively says "AMO, tell me about this extension. OK, it is compatible, let me install the most recent/stable one." Details are at https://wiki.mozilla.org/Services/Sync/Addon_Sync if you are interested. While I recognize syncing specific/pinned versions would be a handy feature in some use cases, it is not something an overwhelming majority of people care about: most people care about getting the latest/greatest/working version of an add-on. Furthermore, syncing specific versions of an add-on has its issues. How do you handle syncing to different Firefox versions where the same add-on version may not be compatible on all of them? How do you reconcile the version to install when multiple versions are present in different sync-connected profiles? There has been talk about adding UX to the Add-on Manager (about:addons) to allow people to select which extensions to be synchronized, rather than the all or nothing approach we have in the initial implementation of add-on sync. If/when that lands, power users could have different/older versions installed on different profiles by opting out of sync for that individual extension. As for the request that versions be pinned, I'm afraid that is a WONTFIX. If you want this behavior today, you'll have to disable add-on sync. If you want to suggest a power-user feature (likely pref-driven) to enable the functionality you desire, we can explore that. But, I'm guessing it will be low priority given more pressing features on Sync's roadmap (https://wiki.mozilla.org/Services/Roadmaps/Sync/Client/Sequence). Sorry :/