diff --git a/src/Controller/AdminPages/BaseAdminController.php b/src/Controller/AdminPages/BaseAdminController.php
index 5e524f4d..6ae67200 100644
--- a/src/Controller/AdminPages/BaseAdminController.php
+++ b/src/Controller/AdminPages/BaseAdminController.php
@@ -43,6 +43,7 @@ use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\HttpFoundation\File\UploadedFile;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\Validator\ConstraintViolationList;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 abstract class BaseAdminController extends AbstractController
 {
@@ -52,11 +53,15 @@ abstract class BaseAdminController extends AbstractController
     protected $twig_template = '';
     protected $route_base = '';
 
-    public function __construct()
+    protected $translator;
+
+    public function __construct(TranslatorInterface $translator)
     {
         if ($this->entity_class === '' || $this->form_class === '' || $this->twig_template === '' || $this->route_base === '') {
             throw new \InvalidArgumentException('You have to override the $entity_class, $form_class, $route_base and $twig_template value in your subclasss!');
         }
+
+        $this->translator = $translator;
     }
 
     protected function _edit(NamedDBElement $entity, Request $request, EntityManagerInterface $em)
@@ -70,6 +75,9 @@ abstract class BaseAdminController extends AbstractController
         if ($form->isSubmitted() && $form->isValid()) {
             $em->persist($entity);
             $em->flush();
+            $this->addFlash('success', $this->translator->trans('entity.edit_flash'));
+        } elseif ($form->isSubmitted() && ! $form->isValid()) {
+            $this->addFlash('error', $this->translator->trans('entity.edit_flash.invalid'));
         }
 
         //Rebuild form, so it is based on the updated data. Important for the parent field!
@@ -96,9 +104,11 @@ abstract class BaseAdminController extends AbstractController
         if ($form->isSubmitted() && $form->isValid()) {
             $em->persist($new_entity);
             $em->flush();
-            //$this->addFlash('success', $translator->trans('part.created_flash'));
+            $this->addFlash('success', $this->translator->trans('entity.created_flash'));
 
             return $this->redirectToRoute($this->route_base . '_edit', ['id' => $new_entity->getID()]);
+        } elseif ($form->isSubmitted() && ! $form->isValid()) {
+            $this->addFlash('error', $this->translator->trans('entity.created_flash.invalid'));
         }
 
         //Import form
diff --git a/src/Controller/PartController.php b/src/Controller/PartController.php
index c04c6174..75a418d2 100644
--- a/src/Controller/PartController.php
+++ b/src/Controller/PartController.php
@@ -70,7 +70,7 @@ class PartController extends AbstractController
      * @param EntityManagerInterface $em
      * @return \Symfony\Component\HttpFoundation\Response
      */
-    public function edit(Part $part, Request $request, EntityManagerInterface $em)
+    public function edit(Part $part, Request $request, EntityManagerInterface $em, TranslatorInterface $translator)
     {
         $this->denyAccessUnlessGranted('edit', $part);
 
@@ -80,7 +80,9 @@ class PartController extends AbstractController
         if ($form->isSubmitted() && $form->isValid()) {
             $em->persist($part);
             $em->flush();
-            $this->addFlash('info', 'part.edited_flash');
+            $this->addFlash('info', $translator->trans('part.edited_flash'));
+        } elseif ($form->isSubmitted() && ! $form->isValid()) {
+            $this->addFlash('error', $translator->trans('part.edited_flash.invalid'));
         }
 
         return $this->render('Parts/edit/edit_part_info.html.twig',
@@ -119,6 +121,8 @@ class PartController extends AbstractController
             $this->addFlash('success', $translator->trans('part.created_flash'));
 
             return $this->redirectToRoute('part_edit', ['id' => $new_part->getID()]);
+        } elseif ($form->isSubmitted() && ! $form->isValid()) {
+            $this->addFlash('error', $translator->trans('part.created_flash.invalid'));
         }
 
         return $this->render('Parts/edit/new_part.html.twig',
diff --git a/src/Entity/Parts/Part.php b/src/Entity/Parts/Part.php
index 03115510..741d073e 100644
--- a/src/Entity/Parts/Part.php
+++ b/src/Entity/Parts/Part.php
@@ -264,7 +264,7 @@ class Part extends AttachmentContainingDBElement
     /**
      * @var float|null How much a single part unit weighs in gramms.
      * @ORM\Column(type="float", nullable=true)
-     * @Assert\Positive()
+     * @Assert\PositiveOrZero()
      */
     protected $mass;