strict compatibility mode enabled - add-ons no longer compatible by default

Magnus Melin mkmelin+mozilla at
Tue Apr 10 20:26:30 UTC 2018

The code upgrade link had a typo, should be


On 10-04-2018 23:04, Magnus Melin wrote:
> Traditionally add-ons have been set to be compatible by default, i.e. 
> not needed an action from the add-on author to continue to function 
> when Thunderbird does a major version update. It has often been the 
> case in recent releases that the add-ons haven't really worked and 
> caused strange bug reports.
> For Thunderbird 60 it doesn't make sense to keep the compatible by 
> default scheme, given the large amount of code changes in core. If the 
> add-on hasn't been updated, it very likely will cause problems - and 
> that's not in anybody's best interest. We therefore made the 
> extensions.strictCompatibility true in bug 1451097, and the change has 
> been landed for the latest Thunderbird 60 beta.
> There are still things to do to mitigate the effect of this change, 
> for instance we need to make sure dictionaries are marked compatible 
> (assuming they are).
> If you're an add-on author, now is the time to make sure your add-on 
> is compatible with Thunderbird 60, scheduled for release shortly after 
> 2018-05-09. You can download the beta from 
> If your add-on is 
> still compatible without any changes, please visit the Mozilla’s 
> Add-ons site and mark it compatible. For your add-on(s), click on 
> “Manage Status & Versions”, then under “Listed versions”, click the 
> link for a version and adjust the versions it is compatible with. If 
> it's not working, you may want to check out the code upgrade guide: 
> Regarding the extensions.strictCompatibility change, please give 
> feedback now even if it's after the fact. If there are too many 
> problems, we may need to reconsider the decision.
> Follow-ups to tb-planning.
>  -Magnus

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