diff --git a/src/Bundle/ChillEventBundle/Controller/ParticipationController.php b/src/Bundle/ChillEventBundle/Controller/ParticipationController.php
index ff6ad92df..54f75f3ae 100644
--- a/src/Bundle/ChillEventBundle/Controller/ParticipationController.php
+++ b/src/Bundle/ChillEventBundle/Controller/ParticipationController.php
@@ -236,6 +236,7 @@ final class ParticipationController extends AbstractController
         return $this->render('@ChillEvent/Participation/new.html.twig', [
             'form' => $form->createView(),
             'participation' => $participation,
+            'ignored_participations' => [],
         ]);
     }
 
diff --git a/src/Bundle/ChillEventBundle/Entity/Event.php b/src/Bundle/ChillEventBundle/Entity/Event.php
index 6d286f2c4..980610092 100644
--- a/src/Bundle/ChillEventBundle/Entity/Event.php
+++ b/src/Bundle/ChillEventBundle/Entity/Event.php
@@ -24,6 +24,7 @@ use DateTime;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\Validator\Constraints as Assert;
 
 /**
  * Class Event.
@@ -40,7 +41,8 @@ class Event implements HasCenterInterface, HasScopeInterface, TrackCreationInter
     use TrackUpdateTrait;
 
     /**
-     * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\Center")
+     * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\Center")A
+     * @Assert\NotNull()
      */
     private ?Center $center = null;
 
@@ -70,6 +72,7 @@ class Event implements HasCenterInterface, HasScopeInterface, TrackCreationInter
 
     /**
      * @ORM\Column(type="string", length=150)
+     * @Assert\NotBlank()
      */
     private ?string $name = null;
 
@@ -84,6 +87,7 @@ class Event implements HasCenterInterface, HasScopeInterface, TrackCreationInter
 
     /**
      * @ORM\ManyToOne(targetEntity="Chill\EventBundle\Entity\EventType")
+     * @Assert\NotNull()
      */
     private ?EventType $type = null;
 
diff --git a/src/Bundle/ChillEventBundle/Entity/Participation.php b/src/Bundle/ChillEventBundle/Entity/Participation.php
index 8076e8f5f..e53ee4181 100644
--- a/src/Bundle/ChillEventBundle/Entity/Participation.php
+++ b/src/Bundle/ChillEventBundle/Entity/Participation.php
@@ -22,6 +22,7 @@ use Chill\MainBundle\Entity\Scope;
 use Chill\PersonBundle\Entity\Person;
 use DateTime;
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
 use Symfony\Component\Validator\Constraints as Assert;
 use Symfony\Component\Validator\Context\ExecutionContextInterface;
 
@@ -36,6 +37,7 @@ use Symfony\Component\Validator\Context\ExecutionContextInterface;
  *     })
  *
  * @ORM\HasLifecycleCallbacks
+ * @UniqueEntity({"event", "person"}, message="event.validation.person_already_participate_to_event")
  */
 class Participation implements \ArrayAccess, HasCenterInterface, HasScopeInterface, TrackUpdateInterface, TrackCreationInterface
 {
@@ -66,7 +68,6 @@ class Participation implements \ArrayAccess, HasCenterInterface, HasScopeInterfa
 
     /**
      * @ORM\ManyToOne(targetEntity="Chill\EventBundle\Entity\Role")
-     * @Assert\NotNull()
      */
     private ?Role $role = null;
 
diff --git a/src/Bundle/ChillEventBundle/Resources/views/Participation/new.html.twig b/src/Bundle/ChillEventBundle/Resources/views/Participation/new.html.twig
index 8374f04ea..620bc7995 100644
--- a/src/Bundle/ChillEventBundle/Resources/views/Participation/new.html.twig
+++ b/src/Bundle/ChillEventBundle/Resources/views/Participation/new.html.twig
@@ -32,7 +32,7 @@
 
 
 
-    <ul class="record_actions">
+    <ul class="record_actions sticky-form-buttons">
         <li class="cancel">
             <a href="{{ path('chill_event__event_show', { 'event_id' : participation.event.id } ) }}" class="btn btn-cancel">
                 {{ 'Back to the event'|trans }}
diff --git a/src/Bundle/ChillEventBundle/config/validation.yaml b/src/Bundle/ChillEventBundle/config/validation.yaml
deleted file mode 100644
index d5c7d2243..000000000
--- a/src/Bundle/ChillEventBundle/config/validation.yaml
+++ /dev/null
@@ -1,26 +0,0 @@
-Chill\EventBundle\Entity\Participation:
-    properties:
-        event: 
-            - NotNull: ~
-        status:
-            - NotNull: ~
-        person:
-            - NotNull: ~
-    constraints:
-        - Callback: isConsistent
-        
-       
-Chill\EventBundle\Entity\Event:
-    properties:
-        name:
-            - Length:
-                min: 3
-                max: 75
-                minMessage: The event name must have at least {{ limit }} characters.
-                maxMessage: The event name must have maximum {{ limit }} characters.
-        type:
-            - NotNull: ~
-        circle:
-            - NotNull: ~
-        center:
-            - NotNull: ~
diff --git a/src/Bundle/ChillEventBundle/translations/validators.fr.yml b/src/Bundle/ChillEventBundle/translations/validators.fr.yml
new file mode 100644
index 000000000..4ebf73ab8
--- /dev/null
+++ b/src/Bundle/ChillEventBundle/translations/validators.fr.yml
@@ -0,0 +1,3 @@
+event:
+    validation:
+        person_already_participate_to_event: L'usager est déjà inscrit à l'événement