diff --git a/backend/migrations/core/084_fix_hero_logo_position.js b/backend/migrations/core/084_fix_hero_logo_position.js
new file mode 100644
index 00000000..d687ee64
--- /dev/null
+++ b/backend/migrations/core/084_fix_hero_logo_position.js
@@ -0,0 +1,21 @@
+/**
+ * Heal events whose hero_logo_position contains a branding-style value
+ * (left/right) caused by a prior bug in adminEvents.js getBrandingDefaults
+ * that mapped branding_logo_position (left/center/right) onto
+ * hero_logo_position (top/center/bottom). Any non-canonical value is
+ * reset to 'top' so subsequent PUTs no longer fail validation.
+ */
+
+exports.up = async function up(knex) {
+  const hasColumn = await knex.schema.hasColumn('events', 'hero_logo_position');
+  if (!hasColumn) return;
+
+  await knex('events')
+    .whereNotIn('hero_logo_position', ['top', 'center', 'bottom'])
+    .update({ hero_logo_position: 'top' });
+};
+
+exports.down = async function down() {
+  // Data correction is not reversible — the original (incorrect) values
+  // are not preserved.
+};
diff --git a/backend/src/routes/adminEvents.js b/backend/src/routes/adminEvents.js
index 7ea50898..a5f0effd 100644
--- a/backend/src/routes/adminEvents.js
+++ b/backend/src/routes/adminEvents.js
@@ -138,14 +138,20 @@ const getDownloadProtectionDefaults = async () => {
   return { enable_devtools_protection: await readBooleanSetting('enable_devtools_protection') };
 };
 
-// Helper to get branding defaults for new events (Feature 7: Branding Inheritance)
+// Helper to get branding defaults for new events (Feature 7: Branding Inheritance).
+//
+// Note: `branding_logo_position` (header bar — left/center/right) is a
+// different concept from `hero_logo_position` (hero block — top/center/
+// bottom) and must NOT be mapped here. A previous version copied the
+// branding value over, which wrote 'left'/'right' into per-event
+// hero_logo_position columns and broke any subsequent PUT validation
+// (#357). Migration 084 heals existing rows.
 const getBrandingDefaults = async () => {
   try {
     const settings = await db('app_settings')
       .whereIn('setting_key', [
         'branding_logo_display_hero',
-        'branding_logo_size',
-        'branding_logo_position'
+        'branding_logo_size'
       ])
       .select('setting_key', 'setting_value');
 
@@ -166,9 +172,6 @@ const getBrandingDefaults = async () => {
       if (s.setting_key === 'branding_logo_size' && value) {
         defaults.hero_logo_size = value;
       }
-      if (s.setting_key === 'branding_logo_position' && value) {
-        defaults.hero_logo_position = value;
-      }
     });
 
     return defaults;