Firefox Sync failing to sync at least ten exensions

More than ten percent of the extensions that I have active with Firefox 54.0.1 on FreeBSD (my main computer) are missing from more recent installations of Firefox on Kubuntu.

A shortlist, including failures for extensions that are inactive:

For the first ten in the shortlist – three of which are FEATURED, all of which have green flags, COMPATIBLE WITH FIREFOX 57+ – can anyone suggest a reasonable explanation for the failures?

Firefox Test Pilot

I imagine that these extensions can not be synchronised because they’re not at True?


The failures to synchronise, which I began noticing a few weeks ago, greatly increase the aggravation of seeking a collection of extensions that might become compatible with each other and with Firefox 57 …

At device momh167-gjp4-hpelitebook8570p-freebsd (Firefox 54.0.1 (64-bit) on FreeBSD-CURRENT), my main computer:

  • 69 active extensions at about:healthreport

At device momh167-gjp4-ergovista621-kubuntu (originally Firefox 54.x, now 55.0b13 (64-bit) on Kubuntu), first sync 20 hours ago, I manually added the ten extensions that were inexplicably not synchronised

At device momh167-gjp4-ergovista621-kubuntu nightly on the same computer (Firefox Nightly 57.0a1 (2017-08-03) (64-bit)), first sync 9 hours ago, I allowed synchronisation alone to attempt installation. Eight of ten appeared. Omissions:

  • MultiSelect Tabs
  • Sea Containers.

A subsequent run resulted in installation of MultiSelect Tabs. One omission:

Total (some of the legacy extensions are forcibly disabled):

  • 56 active extensions.

Back to device momh167-gjp4-ergovista621-kubuntu, I manually added the four Firefox Test Pilot extensions. Result:

  • 71 active extensions.

Back to device momh167-gjp4-ergovista621-kubuntu nightly, the four Firefox Test Pilot extensions did not appear following a sync so I attempted to add them manually.

Test Pilot alone appeared to succeed. It seems impossible to install Containers, Min Vid or Snooze Tabs. Total:

  • 57 active extensions.

@jkingston if I ignore, for a moment, the absence of Containers from 57.0a1: should I expect Sea Containers (reportedly Compatible with Firefox 57+) to be installed with Firefox Sync?

At device momh167-gjp4-macbookpro82-mavericks (Firefox 54.0.1 (64-bit) on OS X 10.9.5 (Mavericks)), first sync 2 hours ago, the first sync seemed endless, I quit after maybe forty-something minutes with:

  • maybe 44 active extensions.

Subsequent runs resulted in more extensions, after a while:

  • 64 active

– including MultiSelect Tabs, omitting Sea Containers.

I manually installed the Test Pilot extension then Containers, Min Vid and Snooze Tabs, then (as it’s disabled manually on all other devices) I disabled Snooze Tabs).

Then a sync, result:

  • 67 active.


  • Sea Containers …

From what I can see there shouldn’t be any reason to not sync sea containers, especially as it’s 57 compatible.

Have you really got 70+ extensions?!


57 aside, it’s remarkable that Sea Containers is missing from 54.0.1 on the Mac.

Does anyone have any idea why all ten extensions at the head of the shortlist failed to synchronise to Kubuntu?


  • 69 active according to about:healthreport
  • 59 inactive according to about:support

Expect a list of active extensions to appear under Concern about WebExtensions exclusive strategy from add-on authors and users

The first ten in the shortlist are also bugged by this when I use AMO on FreeBSD:

… Fix should land in production next Thursday. …

I wonder whether the failures to install on other platforms is an unintended side effect of that bug, maybe only where an initial installation was on FreeBSD. Somehow, I doubt it, but I’ll review the situation after Thursday.

Today I performed two more installations of Firefox, on macOS 10.12.5 (Sierra) – Firefox Nightly (FirefoxAurora) 56.0b2 (64-bit) and Firefox 55.0.1 (64-bit).

In both cases, this extension is missing:

  • Sea Containers.

Both Sum Tabs and Tab Counter should be disabled but on 55.0.1 I found them enabled. I used 55.0.1 to disable them, then synced.

Then in 56.0b2 I synced and found Tab Counter, which should be disabled, enabled …

Cross reference: Mozilla bug 1234400 - Investigate failures to sync addons.