The manifest.json key `applications` is now deprecated and we need your help!

[William Durand]

Hi all!

The `applications` key in WebExtensions `manifest.json` files has been removed in Manifest V3 [1] and everyone should now use `browser_specific_settings` instead.

While Firefox will continue to load Manifest V2 extensions with `applications` keys, some of our tests treat warnings as errors. As a result, we already updated most of the occurrences in m-c. We now need your help to update the *non-test extensions* as part of Bug 1797777 [2].

If you own a module that has extensions, it’d be good to file a bug that depends on Bug 1797777 to update your extensions in the future. In most cases, replacing `applications` with `browser_specific_settings` in manifest files should be transparent. Thank you!

Regards,

William (for the Add-ons team)

[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1797050

[2]: https://bugzilla.mozilla.org/show_bug.cgi?id=1797777