diff --git a/platform/platform-impl/src/com/intellij/ide/actions/WhatsNewAction.java b/platform/platform-impl/src/com/intellij/ide/actions/WhatsNewAction.java
index 656225ba7c36..f2a6673ebc70 100644
--- a/platform/platform-impl/src/com/intellij/ide/actions/WhatsNewAction.java
+++ b/platform/platform-impl/src/com/intellij/ide/actions/WhatsNewAction.java
@@ -125,9 +125,9 @@ public class WhatsNewAction extends AnAction implements DumbAware {
       theme += "-new-ui";
     }
     parameters.put("theme", theme);
-    var locale = Locale.getDefault();
-    if (locale != null) {
-      parameters.put("lang", locale.toLanguageTag().toLowerCase(Locale.ENGLISH));
+    var languageTag = getSiteLanguageTag();
+    if (languageTag != null) {
+      parameters.put("lang", languageTag.toLowerCase(Locale.ENGLISH));
     }
     var request = HTMLEditorProvider.Request.url(Urls.newFromEncoded(url).addParameters(parameters).toExternalForm());
 
@@ -149,4 +149,10 @@ public class WhatsNewAction extends AnAction implements DumbAware {
     var title = IdeBundle.message("update.whats.new", ApplicationNamesInfo.getInstance().getFullProductName());
     HTMLEditorProvider.openEditor(project, title, request);
   }
+
+  private static @Nullable String getSiteLanguageTag() {
+    var language = Locale.getDefault().getLanguage();
+    var region = Locale.getDefault().getCountry();
+    return language.isEmpty() || region.isEmpty() ? null : language + '-' + region;
+  }
 }