Are most of the existing add-ons being sacrificed due to adding support for WebExtension?

Jörg Knobloch jorgk at
Wed Nov 22 06:36:50 UTC 2017

On 22/11/2017 04:08, Eric Moore wrote:
> "In general, there have been many interface/IDL changes over the 
> mozilla57/58/59 period and some changes to JS syntax that most add-ons 
> will require some sort of update to their code. That will distinguish 
> the "maintained" add-ons from the "unmaintained" add-ons some/most of 
> which will stop working.
> ....
> Jörg."
> Who made the decision to essentially kill off legacy add-ons and when 
> was it made?
> Who was aware of that decision?
> Why wasn't this treated as a strategic decision that needed 
> feedback/discussion like was done with getting a new home? 

Hi Eric,

what you write sounds like someone on the Thunderbird project has made 
decisions which negatively affect TB. That is not the case.

That legacy add-ons will be "killed off" is your interpretation. The 
truth is, that most add-ons will need updates to their code. That's 
normal, since interfaces to Mozilla-core change over time. Like 
nsILocalFile was replaced with nsIFile years ago, so no add-on had to 
break when nsILocalFile was finally removed recently. It is true though 
that many interfaces have changed recently as Firefox was moving to 
Quantum (which appears to be quite a success for Mozilla).

Personally I can tell you that I'm using only a handful of add-ons and 
I've informed authors of changes so all the ones I use still work at TB 57.

No one has made any decision, the facts are imposed on us by changes in 
Mozilla-core. All people actively involved with the development of TB 
were aware of the never-ending bustage coming in from Mozilla-core.

The only alternative to following the interface changes is to fork a 
version where most add-ons still work. That would be mozilla57. There 
has been much discussion about a fork. In general, the Council, the 
Engineering Steering Committee and the developer community all agree 
that a fork is undesirable, since we have neither knowledge nor manpower 
to keep up with security patches. So the consensus is to try making it 
to mozilla59 ESR and then keep going as long as possible without a fork.

I hope that answers your query.


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