diff --git a/ontime-back/src/main/java/devkor/ontime_back/service/PreparationUserService.java b/ontime-back/src/main/java/devkor/ontime_back/service/PreparationUserService.java
index 55afeec..b45bb9c 100644
--- a/ontime-back/src/main/java/devkor/ontime_back/service/PreparationUserService.java
+++ b/ontime-back/src/main/java/devkor/ontime_back/service/PreparationUserService.java
@@ -78,6 +78,7 @@ public List<PreparationDto> showAllPreparationUsers(Long userId) {
     protected void handlePreparationUsers(User user, List<PreparationDto> preparationDtoList, boolean shouldDeleteExisting) {
         if (shouldDeleteExisting) {
             preparationUserRepository.deleteByUser(user);
+            preparationUserRepository.flush();
         }
 
         Map<UUID, PreparationUser> preparationMap = new HashMap<>();
@@ -97,6 +98,7 @@ protected void handlePreparationUsers(User user, List<PreparationDto> preparatio
                 .collect(Collectors.toList());
 
         preparationUserRepository.saveAll(preparationUsers);
+        preparationUserRepository.flush();
 
         preparationDtoList.stream()
                 .filter(dto -> dto.getNextPreparationId() != null)