diff --git a/backend/utils/sequelize.js b/backend/utils/sequelize.js
index dc1d387..3ab9d69 100644
--- a/backend/utils/sequelize.js
+++ b/backend/utils/sequelize.js
@@ -105,7 +105,8 @@ const syncModelsWithUpdates = async (models) => {
         if (needsUpdate) {
             console.log('🔄 Schema-Updates nötig - verwende alter: true');
             for (const model of Object.values(models)) { 
-                await model.sync({ alter: true, force: false });
+                // constraints: false verhindert, dass Sequelize Foreign Keys automatisch erstellt
+                await model.sync({ alter: true, force: false, constraints: false });
             }
             console.log('✅ Schema-Updates abgeschlossen');
         } else {
@@ -373,7 +374,8 @@ const getExpectedDefaultValue = (defaultValue) => {
 const updateSchema = async (models) => {
     console.log('🔄 Aktualisiere Datenbankschema...');
     for (const model of Object.values(models)) { 
-        await model.sync({ alter: true, force: false });
+        // constraints: false verhindert, dass Sequelize Foreign Keys automatisch erstellt
+        await model.sync({ alter: true, force: false, constraints: false });
     }
     console.log('✅ Datenbankschema aktualisiert');
 };
@@ -474,7 +476,9 @@ const syncModelsAlways = async (models) => {
             }
             
             try {
-                await model.sync({ alter: true, force: false });
+                // constraints: false verhindert, dass Sequelize Foreign Keys automatisch erstellt
+                // Foreign Keys sollten nur über Migrations verwaltet werden
+                await model.sync({ alter: true, force: false, constraints: false });
             } finally {
                 // Restore VIRTUAL fields after sync
                 for (const [key, attr] of Object.entries(virtualFields)) {