Fixed #30758 Moved changed_data evaluation only in case of updating

django/contrib/admin/utils.py

@@ -489,20 +489,20 @@ def construct_change_message(form, formsets, add):
     Translations are deactivated so that strings are stored untranslated.
     Translation happens later on LogEntry access.
     """
-    # Evaluating `form.changed_data` prior to disabling translations is required
-    # to avoid fields affected by localization from being included incorrectly,
-    # e.g. where date formats differ such as MM/DD/YYYY vs DD/MM/YYYY.
-    changed_data = form.changed_data
-    with translation_override(None):
-        # Deactivate translations while fetching verbose_name for form
-        # field labels and using `field_name`, if verbose_name is not provided.
-        # Translations will happen later on LogEntry access.
-        changed_field_labels = _get_changed_field_labels_from_form(form, changed_data)
-
     change_message = []
     if add:
         change_message.append({'added': {}})
     elif form.changed_data:
+        # Evaluating `form.changed_data` prior to disabling translations is required
+        # to avoid fields affected by localization from being included incorrectly,
+        # e.g. where date formats differ such as MM/DD/YYYY vs DD/MM/YYYY.
+        changed_data = form.changed_data
+        with translation_override(None):
+            # Deactivate translations while fetching verbose_name for form
+            # field labels and using `field_name`, if verbose_name is not provided.
+            # Translations will happen later on LogEntry access.
+            changed_field_labels = _get_changed_field_labels_from_form(form, changed_data)
+
         change_message.append({'changed': {'fields': changed_field_labels}})
     if formsets:
         with translation_override(None):