diff --git a/tools/cldr-apps/js/src/esm/cldrLoad.mjs b/tools/cldr-apps/js/src/esm/cldrLoad.mjs
index ab4d2c9d2d1..bc363df18dc 100644
--- a/tools/cldr-apps/js/src/esm/cldrLoad.mjs
+++ b/tools/cldr-apps/js/src/esm/cldrLoad.mjs
@@ -872,6 +872,9 @@ function loadAllRowsFromJson(json, theDiv) {
     if (json.dataLoadTime) {
       cldrDom.updateIf("dynload", json.dataLoadTime);
     }
+    if (json.loc) {
+      cldrStatus.setCurrentLocale(json.loc); // may replace "USER"
+    }
     cldrStatus.setCurrentSection("");
     cldrStatus.setCurrentPage(json.pageId);
     updateHashAndMenus(); // now that we have a pageid
diff --git a/tools/cldr-apps/js/src/esm/cldrMenu.mjs b/tools/cldr-apps/js/src/esm/cldrMenu.mjs
index b86ea10349d..9f87b6b21fe 100644
--- a/tools/cldr-apps/js/src/esm/cldrMenu.mjs
+++ b/tools/cldr-apps/js/src/esm/cldrMenu.mjs
@@ -127,7 +127,7 @@ function addTopLocales(theDiv, locmap) {
   for (let n in locmap.locmap.topLocales) {
     const topLoc = locmap.locmap.topLocales[n];
     const topLocInfo = locmap.getLocaleInfo(topLoc);
-    if (topLocInfo.special_type !== "scratch") {
+    if (topLocInfo?.special_type !== "scratch") {
       // Skip Sandbox locales here
       addTopLocale(topLoc, theDiv);
     }
@@ -136,7 +136,7 @@ function addTopLocales(theDiv, locmap) {
     for (let n in locmap.locmap.topLocales) {
       const topLoc = locmap.locmap.topLocales[n];
       const topLocInfo = locmap.getLocaleInfo(topLoc);
-      if (topLocInfo.special_type === "scratch") {
+      if (topLocInfo?.special_type === "scratch") {
         // Now only Sandbox locales here
         addTopLocale(topLoc, theDiv);
       }
@@ -421,7 +421,7 @@ function updateLocaleMenu() {
     const locmap = cldrLoad.getTheLocaleMap();
     cldrStatus.setCurrentLocaleName(locmap.getLocaleName(curLocale));
     var bund = locmap.getLocaleInfo(curLocale);
-    if (bund.special_type === "scratch") {
+    if (bund?.special_type === "scratch") {
       prefixMessage = cldrText.get("scratch_locale") + ": ";
     }
     if (bund) {
diff --git a/tools/cldr-apps/js/src/esm/cldrStatus.mjs b/tools/cldr-apps/js/src/esm/cldrStatus.mjs
index b7444674116..da6b0d94d29 100644
--- a/tools/cldr-apps/js/src/esm/cldrStatus.mjs
+++ b/tools/cldr-apps/js/src/esm/cldrStatus.mjs
@@ -226,8 +226,13 @@ function getCurrentLocale() {
 
 function setCurrentLocale(loc) {
   currentLocale = loc;
-  dispatchEvent(new Event("locale"));
-  setRef("currentLocale", loc);
+  // loc may be "USER" temporarily, meaning the back end should choose an appropriate locale
+  // for the current user. The real locale ID should be set when a server response contains it.
+  // In the meantime, postpone calling dispatchEvent or setRef.
+  if ("USER" !== loc) {
+    dispatchEvent(new Event("locale"));
+    setRef("currentLocale", loc);
+  }
 }
 
 /**
diff --git a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/SurveyAjax.java b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/SurveyAjax.java
index cac7304942e..5af20d53db6 100644
--- a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/SurveyAjax.java
+++ b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/SurveyAjax.java
@@ -1055,21 +1055,7 @@ public static CLDRLocale validateLocale(PrintWriter out, String loc, String sess
          * loc can have either - or _; normalize to _
          */
         loc = loc.replace('-', '_');
-        /*
-         * Support "USER" as a "wildcard" for locale name, replacing it with a locale suitable for the
-         * current user, or "fr" (French) as a fallback.
-         */
-        if ("USER".equals(loc) && sess != null && !sess.isEmpty()) {
-            loc = "fr"; // fallback
-            CookieSession.checkForExpiredSessions();
-            CookieSession mySession = CookieSession.retrieve(sess);
-            if (mySession.user != null) {
-                CLDRLocale exLoc = mySession.user.exampleLocale();
-                if (exLoc != null) {
-                    loc = exLoc.getBaseName();
-                }
-            }
-        }
+        loc = UserRegistry.substituteUserWildcardLocale(loc, sess);
         if (loc != null && !loc.isEmpty()) {
             ret = CLDRLocale.getInstance(loc);
         }
diff --git a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/UserRegistry.java b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/UserRegistry.java
index f7782b56237..d7a2f67ef45 100644
--- a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/UserRegistry.java
+++ b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/UserRegistry.java
@@ -50,6 +50,25 @@ public class UserRegistry {
      */
     private static final int ANONYMOUS_USER_COUNT = 20;
 
+    /*
+     * Support "USER" as a "wildcard" for locale name, replacing it with a locale suitable for the
+     * current user, or "fr" (French) as a fallback.
+     */
+    public static String substituteUserWildcardLocale(String loc, String sess) {
+        if ("USER".equals(loc) && sess != null && !sess.isEmpty()) {
+            loc = "fr"; // fallback
+            CookieSession.checkForExpiredSessions();
+            CookieSession mySession = CookieSession.retrieve(sess);
+            if (mySession.user != null) {
+                CLDRLocale exLoc = mySession.user.exampleLocale();
+                if (exLoc != null) {
+                    loc = exLoc.getBaseName();
+                }
+            }
+        }
+        return loc;
+    }
+
     /**
      * Thrown to indicate the caller should log out.
      *
diff --git a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPI.java b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPI.java
index 3ec5ee51b3d..544f482d433 100644
--- a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPI.java
+++ b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPI.java
@@ -232,6 +232,7 @@ public static final class DisplaySets {
 
         public DisplaySets displaySets;
         public JSONArray issues;
+        public String loc; // normally matches requested locale ID unless "USER" is requested
         public String localeDisplayName;
         public Dashboard.ReviewNotification[] notifications;
         public Page page;
diff --git a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPIHelper.java b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPIHelper.java
index 6f0287c80e6..1f5698a8553 100644
--- a/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPIHelper.java
+++ b/tools/cldr-apps/src/main/java/org/unicode/cldr/web/api/VoteAPIHelper.java
@@ -69,7 +69,7 @@ public static class ArgsForGet {
         Boolean getDashboard = false;
 
         public ArgsForGet(String loc, String session) {
-            this.localeId = loc;
+            this.localeId = UserRegistry.substituteUserWildcardLocale(loc, session);
             this.sessionId = session;
         }
     }
@@ -182,6 +182,7 @@ public static RowResponse getRowsResponse(
             r.page.nocontent = true;
         } else {
             r.canModify = UserRegistry.userCanModifyLocale(mySession.user, locale);
+            r.loc = locale.getBaseName();
             r.localeDisplayName = locale.getDisplayName();
             r.page.nocontent = false;
             Collection<DataRow> dataRows = pageData.getAll();