Network extension doesn't get the updated preferred language after changing phone language

We’ve noticed an issue where after running a network extension, if the phone’s language is changed the Locale.preferredLanguages array is not updated and still returns the old array. It only returns the updated array when the app is reinstalled or the phone is restarted. This is unlike the app itself where using the same Locale.preferredLanguages API immediately returns the updated array.

We think this issue is also the cause of notifications that are sent by the network extension being in the previous language as long as the app isn’t reinstalled or the phone is restarted, despite our Localizable file having localised strings for the new language.

Feedback ID: FB20086051

The feedback report includes a sample project with steps on how to reproduce the issue.

Feedback ID: FB20086051

Thanks. And that’s definitely the best path forward here.

Your bug was filed against iOS 26 beta. Is this a regression relatively to iOS 18?

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

The sysdiagnose was taken from our iOS 26 device. We have tested this on all our devices ranging from iOS 15 to iOS 26 and this bug is present on all the versions.

Network extension doesn't get the updated preferred language after changing phone language
 
 
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