diff --git a/backend/migrations/039_club_membership_rbac.sql b/backend/migrations/039_club_membership_rbac.sql
index feee278..7c9ae34 100644
--- a/backend/migrations/039_club_membership_rbac.sql
+++ b/backend/migrations/039_club_membership_rbac.sql
@@ -47,11 +47,15 @@ WHERE t.trainer_id IS NOT NULL
 ON CONFLICT (profile_id, club_id) DO NOTHING;
 
 INSERT INTO club_members (profile_id, club_id, status)
-SELECT DISTINCT elem::int, t.club_id, 'active'
-FROM training_groups t,
-LATERAL jsonb_array_elements_text(t.co_trainer_ids) AS elem
-WHERE jsonb_typeof(t.co_trainer_ids) = 'array'
-  AND jsonb_array_length(t.co_trainer_ids) > 0
+SELECT DISTINCT elem::int, x.club_id, 'active'
+FROM (
+    SELECT club_id, co_trainer_ids
+    FROM training_groups
+    WHERE CASE WHEN jsonb_typeof(co_trainer_ids) = 'array'
+               THEN jsonb_array_length(co_trainer_ids)
+               ELSE 0 END > 0
+) x,
+LATERAL jsonb_array_elements_text(x.co_trainer_ids) AS elem
 ON CONFLICT (profile_id, club_id) DO NOTHING;
 
 INSERT INTO club_member_roles (club_member_id, role_code)
diff --git a/backend/version.py b/backend/version.py
index 0539da1..14e0108 100644
--- a/backend/version.py
+++ b/backend/version.py
@@ -1,6 +1,6 @@
 # Shinkan Jinkendo Version Information
 
-APP_VERSION = "0.8.14"
+APP_VERSION = "0.8.15"
 BUILD_DATE = "2026-05-05"
 DB_SCHEMA_VERSION = "20260505039"
 
@@ -23,6 +23,13 @@ MODULE_VERSIONS = {
 }
 
 CHANGELOG = [
+    {
+        "version": "0.8.15",
+        "date": "2026-05-05",
+        "changes": [
+            "DB 039 Fix: Co-Trainer-Backfill über Subquery + CASE (kein jsonb_array_length/jsonb_array_elements auf Nicht-Arrays durch Planner/LATERAL-Reihenfolge)",
+        ],
+    },
     {
         "version": "0.8.14",
         "date": "2026-05-05",
diff --git a/frontend/src/version.js b/frontend/src/version.js
index efcbfce..a3383e9 100644
--- a/frontend/src/version.js
+++ b/frontend/src/version.js
@@ -1,6 +1,6 @@
 // Shinkan Jinkendo Frontend Version
 
-export const APP_VERSION = "0.8.14"
+export const APP_VERSION = "0.8.15"
 export const BUILD_DATE = "2026-05-05"
 
 export const PAGE_VERSIONS = {