diff --git a/backend/utils/syncDatabase.js b/backend/utils/syncDatabase.js
index 8e369d9..95f82c2 100644
--- a/backend/utils/syncDatabase.js
+++ b/backend/utils/syncDatabase.js
@@ -408,6 +408,32 @@ const syncDatabase = async () => {
             console.warn('⚠️  Konnte Vocab-Trainer Tabellen nicht sicherstellen:', e?.message || e);
         }
 
+        // Migration: ChurchApplication supervisor_id nullable machen (kritisch für Funktionalität)
+        console.log("Making church_application supervisor_id nullable...");
+        try {
+            await sequelize.query(`
+                DO $$
+                BEGIN
+                    -- Prüfe ob supervisor_id NOT NULL Constraint existiert
+                    IF EXISTS (
+                        SELECT 1 FROM information_schema.columns
+                        WHERE table_schema = 'falukant_data' 
+                        AND table_name = 'church_application' 
+                        AND column_name = 'supervisor_id'
+                        AND is_nullable = 'NO'
+                    ) THEN
+                        ALTER TABLE falukant_data.church_application 
+                        ALTER COLUMN supervisor_id DROP NOT NULL;
+                        RAISE NOTICE 'supervisor_id NOT NULL Constraint entfernt';
+                    END IF;
+                END
+                $$;
+            `);
+            console.log("✅ church_application supervisor_id ist jetzt nullable");
+        } catch (e) {
+            console.warn('⚠️  Konnte church_application supervisor_id nicht nullable machen:', e?.message || e);
+        }
+
         // Relationship-/Marriage-Proposal-Änderungen loggen (keine Einträge löschen; ohne db:migrate)
         console.log("Ensuring relationship change log (falukant) exists...");
         try {
@@ -731,6 +757,32 @@ const syncDatabaseForDeployment = async () => {
             console.warn('⚠️  Konnte Transport-Spalten nicht nullable machen:', e?.message || e);
         }
 
+        // Migration: ChurchApplication supervisor_id nullable machen
+        console.log("Making church_application supervisor_id nullable...");
+        try {
+            await sequelize.query(`
+                DO $$
+                BEGIN
+                    -- Prüfe ob supervisor_id NOT NULL Constraint existiert
+                    IF EXISTS (
+                        SELECT 1 FROM information_schema.columns
+                        WHERE table_schema = 'falukant_data' 
+                        AND table_name = 'church_application' 
+                        AND column_name = 'supervisor_id'
+                        AND is_nullable = 'NO'
+                    ) THEN
+                        ALTER TABLE falukant_data.church_application 
+                        ALTER COLUMN supervisor_id DROP NOT NULL;
+                        RAISE NOTICE 'supervisor_id NOT NULL Constraint entfernt';
+                    END IF;
+                END
+                $$;
+            `);
+            console.log("✅ church_application supervisor_id ist jetzt nullable");
+        } catch (e) {
+            console.warn('⚠️  Konnte church_application supervisor_id nicht nullable machen:', e?.message || e);
+        }
+
         // Cleanup: Entferne verwaiste Einträge vor Schema-Updates
         console.log("Cleaning up orphaned entries...");
         try {
@@ -882,9 +934,9 @@ const syncDatabaseForDeployment = async () => {
                         SELECT id FROM falukant_type.church_office_type
                     ) OR region_id NOT IN (
                         SELECT id FROM falukant_data.region
-                    ) OR supervisor_id NOT IN (
+                    ) OR (supervisor_id IS NOT NULL AND supervisor_id NOT IN (
                         SELECT id FROM falukant_data.character
-                    );
+                    ));
                 `, 30000, 'church_application cleanup');
                 const deletedCount12 = result12[1] || 0;
                 if (deletedCount12 > 0) {