diff --git a/src/Entity/Parts/PartTraits/BasicPropertyTrait.php b/src/Entity/Parts/PartTraits/BasicPropertyTrait.php
index 57941140..200c1559 100644
--- a/src/Entity/Parts/PartTraits/BasicPropertyTrait.php
+++ b/src/Entity/Parts/PartTraits/BasicPropertyTrait.php
@@ -46,6 +46,7 @@ use App\Entity\Parts\Category;
 use App\Entity\Parts\Footprint;
 use App\Security\Annotations\ColumnSecurity;
 use App\Validator\Constraints\Selectable;
+use Symfony\Component\Validator\Constraints as Assert;
 
 trait BasicPropertyTrait
 {
@@ -83,6 +84,7 @@ trait BasicPropertyTrait
      * @ORM\JoinColumn(name="id_category", referencedColumnName="id", nullable=false)
      * @ColumnSecurity(prefix="category", type="App\Entity\Parts\Category")
      * @Selectable()
+     * @Assert\NotNull(message="validator.select_valid_category")
      */
     protected $category;
 
@@ -196,7 +198,7 @@ trait BasicPropertyTrait
      *
      * @return $this
      */
-    public function setCategory(Category $category): self
+    public function setCategory(?Category $category): self
     {
         $this->category = $category;
 
diff --git a/src/Form/Part/PartBaseType.php b/src/Form/Part/PartBaseType.php
index bb7d4471..6be12032 100644
--- a/src/Form/Part/PartBaseType.php
+++ b/src/Form/Part/PartBaseType.php
@@ -131,6 +131,9 @@ class PartBaseType extends AbstractType
                 'label' => 'part.edit.category',
                 'disable_not_selectable' => true,
                 'disabled' => ! $this->security->isGranted('category.edit', $part),
+                'constraints' => [
+
+                ]
             ])
             ->add('footprint', StructuralEntityType::class, [
                 'class' => Footprint::class,
diff --git a/translations/validators.de.xlf b/translations/validators.de.xlf
index fdf7caf3..4fbfc2ab 100644
--- a/translations/validators.de.xlf
+++ b/translations/validators.de.xlf
@@ -167,5 +167,11 @@
         <target>Der Benutzername darf nur Buchstaben, Zahlen, Unterstriche, Punkte, Plus- oder Minuszeichen enthalten.</target>
       </segment>
     </unit>
+    <unit id="ayNr6QK" name="validator.select_valid_category">
+      <segment>
+        <source>validator.select_valid_category</source>
+        <target>Bitte wählen Sie eine gültige Kategorie.</target>
+      </segment>
+    </unit>
   </file>
 </xliff>
diff --git a/translations/validators.en.xlf b/translations/validators.en.xlf
index b408eaaa..2408970a 100644
--- a/translations/validators.en.xlf
+++ b/translations/validators.en.xlf
@@ -185,5 +185,11 @@
         <target>You can not assign children element as parent (This would cause loops).</target>
       </segment>
     </unit>
+    <unit id="ayNr6QK" name="validator.select_valid_category">
+      <segment>
+        <source>validator.select_valid_category</source>
+        <target>Please select a valid category!</target>
+      </segment>
+    </unit>
   </file>
 </xliff>