How do I deploy a language pack?

[untrustedWorldHavok]

I'm attempting to write a policy to deploy spell checking for en-GB as a default. My system locale is not en-GB but I don't think that matters.

I cannot find any documentation on how to use a policy to set the language, nor download any relevant language pack.

For reference, the official language pack is at https://addons.mozilla.org/en-US/firefox/addon/english-gb-language-pack/ , this links to https://addons.mozilla.org/firefox/downloads/file/4565583/english_gb_language_pack-142.0.20250827.4350.xpi which is version pinned. If I attempt to download the latest via addons.mozilla.org/firefox/downloads/latest/english-gb-language-pack/addon-4757633-latest.xpi I get the error 'Language: English (GB) could not be installed because it is not compatible with Firefox 142.0.1'. The version history indicates language pack versions are tightly bound to firefox versions - https://addons.mozilla.org/en-US/firefox/addon/english-gb-language-pack/versions/ , I'm unsure why that is.

Even once the language pack is deployed, I cannot see any policy which sets the preferred spelling language.

[mkaply]

I have an article that has some info on this:

https://support.mozilla.org/kb/deploying-firefox-language-packs

The most important bit it has is where to get language packs.

The problem you are running into is that the language packs on AMO are "later" than the current release (usually beta).

So you need to deploy the language pack that is associated with the version that you are shipping.

The reason language packs are tightly bound is because there are strings that are specific to that version.

To set the the locale, you use the RequestedLocales policy:

https://mozilla.github.io/policy-templates/#requestedlocales

I am working on a spellchecker default policy, but the code in Firefox is very complicated, so we don't have this right now.

[nyabinary]

I have an article that has some info on this:

https://support.mozilla.org/kb/deploying-firefox-language-packs

The most important bit it has is where to get language packs.

The problem you are running into is that the language packs on AMO are "later" than the current release (usually beta).

So you need to deploy the language pack that is associated with the version that you are shipping.

The reason language packs are tightly bound is because there are strings that are specific to that version.

To set the the locale, you use the RequestedLocales policy:

https://mozilla.github.io/policy-templates/#requestedlocales

I am working on a spellchecker default policy, but the code in Firefox is very complicated, so we don't have this right now.

requestedlocales dont work on nightly by the way, might want to mention it on the notes :3

[mkaply]

requestedlocales dont work on nightly by the way, might want to mention it on the notes :3

There are no language packs for nightly, so it can't really.