210554 2020-04-15 09:55:56 -0700 REGRESSION (STP 100-104): Incorrect locale and language codes for Russian 2020-09-14 20:23:39 -0700 1 1 1 Unclassified WebKit DOM Other Unspecified Unspecified RESOLVED CONFIGURATION CHANGED InRadar P2 Normal --- 1 ap ysuzuki david keith_miller mmaxfield webkit-bug-importer ysuzuki oldest_to_newest 1641843 0 ap 2020-04-15 09:55:56 -0700 [new Intl.DateTimeFormat("default").resolvedOptions().locale, new Intl.DateTimeFormat().resolvedOptions().locale, new Intl.DateTimeFormat().format(new Date()), navigator.language] Shipping Safari and STP 100: ["ru", "ru", "15.04.2020", "ru"] STP 104: ["ru-RU", "ru-RU", "15.04.2020", "ru-ru"] Chrome: ["ru", "ru", "15.04.2020", "ru-RU"] I am not aware of any reasons to change shipping Safari behavior, and definitely not to be different from Chrome. 1641844 1 webkit-bug-importer 2020-04-15 09:56:06 -0700 <rdar://problem/61832849> 1641846 2 ap 2020-04-15 09:58:40 -0700 Here is my system configuration, which actually surprised me, but ru-RU isn't there for sure: $ defaults read -g AppleLanguages ( "ru-US", "en-US", "zh-Hant-US", "ja-US", "ko-US", "vi-US", "de-US", "fr-US", "zh-Hans-US", hi ) $ defaults read -g AppleLocale ru_US 1688562 3 ysuzuki 2020-09-14 20:23:39 -0700 This is fixed internally for newer STP.