diff --git a/src/Bundle/ChillCalendarBundle/Entity/Calendar.php b/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
index 6c7e9e503..b1a6f8850 100644
--- a/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
+++ b/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
@@ -31,6 +31,7 @@ use Doctrine\Common\Collections\Criteria;
 use Doctrine\ORM\Mapping as ORM;
 use LogicException;
 use Symfony\Component\Serializer\Annotation as Serializer;
+use Symfony\Component\Validator\Constraints as Assert;
 use Symfony\Component\Validator\Constraints\NotBlank;
 
 use Symfony\Component\Validator\Constraints\Range;
@@ -113,6 +114,7 @@ class Calendar implements TrackCreationInterface, TrackUpdateInterface
     /**
      * @ORM\Column(type="datetime_immutable", nullable=false)
      * @Serializer\Groups({"calendar:read", "read"})
+     * @Assert\NotNull(message="calendar.An end date is required")
      */
     private ?DateTimeImmutable $endDate = null;
 
@@ -139,12 +141,14 @@ class Calendar implements TrackCreationInterface, TrackUpdateInterface
     /**
      * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\Location")
      * @Serializer\Groups({"read"})
+     * @Assert\NotNull(message="calendar.A location is required")
      */
     private ?Location $location = null;
 
     /**
      * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\User")
      * @Serializer\Groups({"calendar:read", "read"})
+     * @Assert\NotNull(message="calendar.A main user is mandatory")
      */
     private ?User $mainUser = null;
 
@@ -152,6 +156,7 @@ class Calendar implements TrackCreationInterface, TrackUpdateInterface
      * @ORM\ManyToMany(targetEntity="Chill\PersonBundle\Entity\Person")
      * @ORM\JoinTable(name="chill_calendar.calendar_to_persons")
      * @Serializer\Groups({"calendar:read", "read"})
+     * @Assert\Count(min=1, minMessage="calendar.At least {{ limit }} person is required.")
      */
     private Collection $persons;
 
@@ -181,6 +186,7 @@ class Calendar implements TrackCreationInterface, TrackUpdateInterface
     /**
      * @ORM\Column(type="datetime_immutable", nullable=false)
      * @Serializer\Groups({"calendar:read", "read"})
+     * @Assert\NotNull(message="calendar.A start date is required")
      */
     private ?DateTimeImmutable $startDate = null;
 
diff --git a/src/Bundle/ChillCalendarBundle/Form/CalendarType.php b/src/Bundle/ChillCalendarBundle/Form/CalendarType.php
index ebd62fb2e..1a38c1ba6 100644
--- a/src/Bundle/ChillCalendarBundle/Form/CalendarType.php
+++ b/src/Bundle/ChillCalendarBundle/Form/CalendarType.php
@@ -101,7 +101,7 @@ class CalendarType extends AbstractType
                     return $res;
                 },
                 static function (?string $dateAsString): ?DateTimeImmutable {
-                    if ('' === $dateAsString) {
+                    if ('' === $dateAsString || null === $dateAsString) {
                         return null;
                     }
 
@@ -122,7 +122,7 @@ class CalendarType extends AbstractType
                     return $res;
                 },
                 static function (?string $dateAsString): ?DateTimeImmutable {
-                    if ('' === $dateAsString) {
+                    if ('' === $dateAsString || null === $dateAsString) {
                         return null;
                     }
 
diff --git a/src/Bundle/ChillCalendarBundle/Resources/views/Calendar/listByAccompanyingCourse.html.twig b/src/Bundle/ChillCalendarBundle/Resources/views/Calendar/listByAccompanyingCourse.html.twig
index 1407f5855..e71c3f7d4 100644
--- a/src/Bundle/ChillCalendarBundle/Resources/views/Calendar/listByAccompanyingCourse.html.twig
+++ b/src/Bundle/ChillCalendarBundle/Resources/views/Calendar/listByAccompanyingCourse.html.twig
@@ -82,14 +82,17 @@
                         } %}
                     </div>
 
-                    {% if calendar.comment.comment is not empty %}
-                    <div class="item-col comment">
-                        {{ calendar.comment|chill_entity_render_box( { 'limit_lines': 3, 'metadata': false } ) }}
-                    </div>
-                    {% endif %}
                 </div>
                 {% endif %}
 
+                {% if calendar.comment.comment is not empty %}
+                    <div class="item-row details separator">
+                        <div class="item-col comment">
+                            {{ calendar.comment|chill_entity_render_box( { 'limit_lines': 3, 'metadata': false } ) }}
+                        </div>
+                    </div>
+                {% endif %}
+
                 {% if calendar.location is not empty %}
                     <div class="item-row separator">
                         <div>
diff --git a/src/Bundle/ChillCalendarBundle/translations/validators.fr.yml b/src/Bundle/ChillCalendarBundle/translations/validators.fr.yml
new file mode 100644
index 000000000..7d9be7a91
--- /dev/null
+++ b/src/Bundle/ChillCalendarBundle/translations/validators.fr.yml
@@ -0,0 +1,7 @@
+calendar:
+    At least {{ limit }} person is required.: Au moins {{ limit }} personne doit être associée à ce rendez-vous
+    An end date is required: Indiquez une date et heure de fin
+    A start date is required: Indiquez une date et heure de début
+    A location is required: Indiquez un lieu
+    A main user is mandator: Indiquez un utilisateur principal
+