PSA: Legacy extensions disabled by default on Nightly

Kevin Jones kevinhowjones at
Sun Aug 13 12:20:44 UTC 2017

Thanks Andrew :-)

I want to mention that on the AMO site, legacy addons now appear with a
greyed-out "install" button.  This happens when even in Nightly with
`extensions.legacy.enabled=true`.  The pref works and I can run legacy
extensions, but the AMO site does not allow the user to install updates,
including fixes for addons broken by removal of deprecated code.

"there is a preference that Nightly users can flip to re-enable loading of
legacy extensions in the addons manager"

I don't seem to find anything in the addon manager to accomplish this, I
had to take a guess at the name of the pref and flip it manually.

Kudos for another major step in the advancement into the next era!


On Thu, Aug 10, 2017 at 10:00 AM, Andrew Swan <aswan at> wrote:

> After lots of recent discussion, it is finally happening.  The patch to
> flip the default setting to disallow legacy extensions is in autoland at
> the moment and, barring some snafu, should be in tomorrow's Nightly
> builds.  This is a bit anti-climactic since a few other changes that have
> already landed that broke a bunch of existing extensions.
> Also this has been discussed in a few other threads but repeating here for
> folks that may have missed it: there is a preference that Nightly users can
> flip to re-enable loading of legacy extensions in the addons manager (of
> course this setting won't magically make extensions that rely on the sdk or
> any changed internal interfaces work).  We will continue to honor this
> preference in Nightly builds and in unbranded builds, but when 57 (and
> later versions) go to beta and eventually to release, that preference will
> be ignored.  If you're familiar with addon signing and the circumstances in
> which we allow it to be disabled, legacy extensions are handled in the same
> way.
> If you notice any problems or have questions, you can contact me directly,
> use the dev-addons mailing list, or drop into #webextensions on IRC.
> :highfive:s all around!
> -Andrew
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