diff --git a/backend/utils/syncDatabase.js b/backend/utils/syncDatabase.js
index f12c305..e9f5ff8 100644
--- a/backend/utils/syncDatabase.js
+++ b/backend/utils/syncDatabase.js
@@ -82,7 +82,21 @@ const syncDatabase = async () => {
                     console.log(`✅ ${deletedCount2} verwaiste stock Einträge entfernt`);
                 }
 
-                if (deletedCount1 === 0 && deletedCount2 === 0) {
+                // Cleanup knowledge mit ungültigen character_id oder product_id
+                const result3 = await sequelize.query(`
+                    DELETE FROM falukant_data.knowledge
+                    WHERE character_id NOT IN (
+                        SELECT id FROM falukant_data.character
+                    ) OR product_id NOT IN (
+                        SELECT id FROM falukant_type.product
+                    );
+                `);
+                const deletedCount3 = result3[1] || 0;
+                if (deletedCount3 > 0) {
+                    console.log(`✅ ${deletedCount3} verwaiste knowledge Einträge entfernt`);
+                }
+
+                if (deletedCount1 === 0 && deletedCount2 === 0 && deletedCount3 === 0) {
                     console.log("✅ Keine verwaisten Einträge gefunden");
                 }
             } catch (e) {
@@ -235,7 +249,21 @@ const syncDatabaseForDeployment = async () => {
                 console.log(`✅ ${deletedCount2} verwaiste stock Einträge entfernt`);
             }
 
-            if (deletedCount1 === 0 && deletedCount2 === 0) {
+            // Cleanup knowledge mit ungültigen character_id oder product_id
+            const result3 = await sequelize.query(`
+                DELETE FROM falukant_data.knowledge
+                WHERE character_id NOT IN (
+                    SELECT id FROM falukant_data.character
+                ) OR product_id NOT IN (
+                    SELECT id FROM falukant_type.product
+                );
+            `);
+            const deletedCount3 = result3[1] || 0;
+            if (deletedCount3 > 0) {
+                console.log(`✅ ${deletedCount3} verwaiste knowledge Einträge entfernt`);
+            }
+
+            if (deletedCount1 === 0 && deletedCount2 === 0 && deletedCount3 === 0) {
                 console.log("✅ Keine verwaisten Einträge gefunden");
             }
         } catch (e) {