diff --git a/src/CoreBundle/Entity/Message.php b/src/CoreBundle/Entity/Message.php
index 89c8a4cb57..a0ea9dc12f 100644
--- a/src/CoreBundle/Entity/Message.php
+++ b/src/CoreBundle/Entity/Message.php
@@ -59,19 +59,17 @@ class Message
     protected $sendDate;
 
     /**
-     * @var string
      * @Assert\NotBlank
      * @ORM\Column(name="title", type="string", length=255, nullable=false)
      */
-    protected $title;
+    protected string $title;
 
     /**
-     * @var string
      * @Assert\NotBlank
      *
      * @ORM\Column(name="content", type="text", nullable=false)
      */
-    protected $content;
+    protected string $content;
 
     /**
      * @var int
@@ -120,16 +118,15 @@ class Message
      */
     public function __construct()
     {
+        $this->content = '';
         $this->attachments = new ArrayCollection();
         $this->likes = new ArrayCollection();
     }
 
     /**
      * Set userSender.
-     *
-     * @return Message
      */
-    public function setUserSender(User $userSender)
+    public function setUserSender(User $userSender): self
     {
         $this->userSender = $userSender;
 
@@ -138,20 +135,16 @@ class Message
 
     /**
      * Get userSender.
-     *
-     * @return User
      */
-    public function getUserSender()
+    public function getUserSender(): User
     {
         return $this->userSender;
     }
 
     /**
      * Set userReceiver.
-     *
-     * @return Message
      */
-    public function setUserReceiver(User $userReceiver)
+    public function setUserReceiver(User $userReceiver): self
     {
         $this->userReceiver = $userReceiver;
 
diff --git a/src/CoreBundle/Entity/PersonalAgenda.php b/src/CoreBundle/Entity/PersonalAgenda.php
index 51b7fc86f9..5d4cd1744d 100644
--- a/src/CoreBundle/Entity/PersonalAgenda.php
+++ b/src/CoreBundle/Entity/PersonalAgenda.php
@@ -6,6 +6,7 @@ namespace Chamilo\CoreBundle\Entity;
 
 use Chamilo\CoreBundle\Traits\UserTrait;
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\Validator\Constraints as Assert;
 
 /**
  * PersonalAgenda.
@@ -28,19 +29,17 @@ class PersonalAgenda
     protected $id;
 
     /**
-     * @var User
-     *
      * @ORM\ManyToOne(targetEntity="Chamilo\CoreBundle\Entity\User", inversedBy="personalAgendas")
      * @ORM\JoinColumn(name="user", referencedColumnName="id", onDelete="CASCADE")
      */
-    protected $user;
+    protected User $user;
 
     /**
-     * @var string
+     * @Assert\NotBlank()
      *
      * @ORM\Column(name="title", type="text", nullable=true)
      */
-    protected $title;
+    protected string $title;
 
     /**
      * @var string
diff --git a/src/CoreBundle/Entity/PersonalFile.php b/src/CoreBundle/Entity/PersonalFile.php
index 2a801f026a..6a96096bf6 100644
--- a/src/CoreBundle/Entity/PersonalFile.php
+++ b/src/CoreBundle/Entity/PersonalFile.php
@@ -27,11 +27,9 @@ class PersonalFile extends AbstractResource implements ResourceInterface
     protected $id;
 
     /**
-     * @var string
-     *
      * @ORM\Column(name="name", type="string", length=255, nullable=false)
      */
-    protected $name;
+    protected string $name;
 
     public function __construct()
     {
diff --git a/src/CoreBundle/Entity/ResourceFile.php b/src/CoreBundle/Entity/ResourceFile.php
index 56ed78b2dc..06c053ca9a 100644
--- a/src/CoreBundle/Entity/ResourceFile.php
+++ b/src/CoreBundle/Entity/ResourceFile.php
@@ -77,30 +77,24 @@ class ResourceFile
     protected $id;
 
     /**
-     * @var string
-     *
      * @Assert\NotBlank()
      * @Groups({"resource_file:read", "resource_node:read", "document:read"})
      *
      * @ORM\Column(type="string", length=255)
      */
-    protected $name;
+    protected string $name;
 
     /**
-     * @var string
-     *
      * @Groups({"resource_file:read", "resource_node:read", "document:read"})
      * @ORM\Column(type="text", nullable=true)
      */
-    protected $mimeType;
+    protected string $mimeType;
 
     /**
-     * @var string
-     *
      * @Groups({"resource_file:read", "resource_node:read", "document:read"})
      * @ORM\Column(type="text", nullable=true)
      */
-    protected $originalName;
+    protected string $originalName;
 
     /**
      * @var string
@@ -142,11 +136,9 @@ class ResourceFile
     protected $crop;
 
     /**
-     * @var ResourceNode
-     *
      * @ORM\OneToOne(targetEntity="Chamilo\CoreBundle\Entity\ResourceNode", mappedBy="resourceFile")
      */
-    protected $resourceNode;
+    protected ResourceNode $resourceNode;
 
     /**
      * @var array
diff --git a/src/CoreBundle/Entity/ResourceNode.php b/src/CoreBundle/Entity/ResourceNode.php
index 7f9dfdf3f2..042f7e04d8 100644
--- a/src/CoreBundle/Entity/ResourceNode.php
+++ b/src/CoreBundle/Entity/ResourceNode.php
@@ -63,7 +63,7 @@ class ResourceNode
      *
      * @ORM\Column(name="title", type="string", length=255, nullable=false)
      */
-    protected $title;
+    protected string $title;
 
     /**
      * @Assert\NotBlank()
@@ -71,15 +71,13 @@ class ResourceNode
      * @Gedmo\Slug(fields={"title"})
      * @ORM\Column(name="slug", type="string", length=255, nullable=false)
      */
-    protected $slug;
+    protected string $slug;
 
     /**
-     * @var ResourceType
-     *
      * @ORM\ManyToOne(targetEntity="ResourceType", inversedBy="resourceNodes")
      * @ORM\JoinColumn(name="resource_type_id", referencedColumnName="id", nullable=false)
      */
-    protected $resourceType;
+    protected ResourceType $resourceType;
 
     /**
      * @ApiSubresource()
@@ -91,14 +89,14 @@ class ResourceNode
     protected $resourceLinks;
 
     /**
-     * @var ResourceFile available file for this node
+     * ResourceFile available file for this node
      *
      * @Groups({"resource_node:read", "resource_node:write", "document:read", "document:write"})
      *
      * @ORM\OneToOne(targetEntity="ResourceFile", inversedBy="resourceNode", orphanRemoval=true)
      * @ORM\JoinColumn(name="resource_file_id", referencedColumnName="id", onDelete="CASCADE")
      */
-    protected $resourceFile;
+    protected ResourceFile $resourceFile;
 
     /**
      * @var User the creator of this node
@@ -107,7 +105,7 @@ class ResourceNode
      * @ORM\ManyToOne(targetEntity="Chamilo\CoreBundle\Entity\User", inversedBy="resourceNodes")
      * @ORM\JoinColumn(name="creator_id", referencedColumnName="id", nullable=true, onDelete="CASCADE")
      */
-    protected $creator;
+    protected User $creator;
 
     /**
      * @ApiSubresource()
diff --git a/src/CoreBundle/Entity/ResourceType.php b/src/CoreBundle/Entity/ResourceType.php
index 8f976d48de..d05e3aeb79 100644
--- a/src/CoreBundle/Entity/ResourceType.php
+++ b/src/CoreBundle/Entity/ResourceType.php
@@ -28,22 +28,19 @@ class ResourceType
      *
      * @Assert\NotBlank()
      */
-    protected $name;
+    protected string $name;
 
     /**
      * @ORM\ManyToOne(targetEntity="Chamilo\CoreBundle\Entity\Tool", inversedBy="resourceTypes")
      * @ORM\JoinColumn(name="tool_id", referencedColumnName="id")
      */
-    protected $tool;
+    protected Tool $tool;
 
     /**
      * @ORM\OneToMany(targetEntity="Chamilo\CoreBundle\Entity\ResourceNode", mappedBy="resourceType", cascade={"persist", "remove"})
      */
     protected $resourceNodes;
 
-    /**
-     * Constructor.
-     */
     public function __construct()
     {
     }
diff --git a/src/CoreBundle/Entity/ScheduledAnnouncement.php b/src/CoreBundle/Entity/ScheduledAnnouncement.php
index e1e080f72d..09ce008562 100644
--- a/src/CoreBundle/Entity/ScheduledAnnouncement.php
+++ b/src/CoreBundle/Entity/ScheduledAnnouncement.php
@@ -24,18 +24,14 @@ class ScheduledAnnouncement
     protected $id;
 
     /**
-     * @var string
-     *
      * @ORM\Column(name="subject", type="string", length=255, nullable=false, unique=false)
      */
-    protected $subject;
+    protected string $subject;
 
     /**
-     * @var string
-     *
      * @ORM\Column(name="message", type="text", unique=false)
      */
-    protected $message;
+    protected string $message;
 
     /**
      * @var \DateTime
@@ -65,9 +61,6 @@ class ScheduledAnnouncement
      */
     protected $cId;
 
-    /**
-     * Constructor.
-     */
     public function __construct()
     {
     }
diff --git a/src/CoreBundle/Entity/Session.php b/src/CoreBundle/Entity/Session.php
index 6c361aeb07..e5f6e74853 100644
--- a/src/CoreBundle/Entity/Session.php
+++ b/src/CoreBundle/Entity/Session.php
@@ -161,32 +161,27 @@ class Session
     protected $showDescription;
 
     /**
-     * @var int
-     *
      * @ORM\Column(name="duration", type="integer", nullable=true)
      */
-    protected $duration;
+    protected int $duration;
 
     /**
-     * @var int
      * @Groups({"session:read"})
      * @ORM\Column(name="nbr_courses", type="smallint", nullable=true, unique=false)
      */
-    protected $nbrCourses;
+    protected int $nbrCourses;
 
     /**
-     * @var int
      * @Groups({"session:read"})
      * @ORM\Column(name="nbr_users", type="integer", nullable=true, unique=false)
      */
-    protected $nbrUsers;
+    protected int $nbrUsers;
 
     /**
-     * @var int
      * @Groups({"session:read"})
      * @ORM\Column(name="nbr_classes", type="integer", nullable=true, unique=false)
      */
-    protected $nbrClasses;
+    protected int $nbrClasses;
 
     /**
      * @var User
@@ -314,6 +309,7 @@ class Session
         $this->description = '';
         $this->nbrClasses = 0;
         $this->nbrUsers = 0;
+        $this->nbrCourses = 0;
         $this->sendSubscriptionNotification = false;
         $this->displayStartDate = new \DateTime();
         $this->displayEndDate = new \DateTime();
@@ -333,38 +329,24 @@ class Session
         $this->studentPublications = new ArrayCollection();
     }
 
-    /**
-     * @return string
-     */
-    public function __toString()
+    public function __toString(): string
     {
         return (string) $this->getName();
     }
 
-    /**
-     * @return int
-     */
-    public function getDuration()
+    public function getDuration(): int
     {
         return $this->duration;
     }
 
-    /**
-     * @param int $duration
-     *
-     * @return $this
-     */
-    public function setDuration($duration)
+    public function setDuration(int $duration): self
     {
         $this->duration = $duration;
 
         return $this;
     }
 
-    /**
-     * @return string
-     */
-    public function getShowDescription()
+    public function getShowDescription(): bool
     {
         return $this->showDescription;
     }
diff --git a/src/CoreBundle/Entity/Skill.php b/src/CoreBundle/Entity/Skill.php
index a441cfbb86..385aee3838 100644
--- a/src/CoreBundle/Entity/Skill.php
+++ b/src/CoreBundle/Entity/Skill.php
@@ -57,30 +57,27 @@ class Skill
     protected $id;
 
     /**
-     * @var string
      * @Groups({"skill:read", "skill:write"})
      * @Assert\NotBlank()
      *
      * @ORM\Column(name="name", type="string", length=255, nullable=false)
      */
-    protected $name;
+    protected string $name;
 
     /**
-     * @var string
      * @Assert\NotBlank()
      * @Groups({"skill:read", "skill:write"})
      *
      * @ORM\Column(name="short_code", type="string", length=100, nullable=false)
      */
-    protected $shortCode;
+    protected string $shortCode;
 
     /**
-     * @var string
      * @Groups({"skill:read", "skill:write"})
      *
      * @ORM\Column(name="description", type="text", nullable=false)
      */
-    protected $description;
+    protected string $description;
 
     /**
      * @var int
@@ -119,11 +116,9 @@ class Skill
      */
     protected $updatedAt;
 
-    /**
-     * Constructor.
-     */
     public function __construct()
     {
+        $this->description = '';
         $this->status = self::STATUS_ENABLED;
     }
 
diff --git a/src/CourseBundle/Entity/CAttendance.php b/src/CourseBundle/Entity/CAttendance.php
index f5721d7f23..43e44ede0e 100644
--- a/src/CourseBundle/Entity/CAttendance.php
+++ b/src/CourseBundle/Entity/CAttendance.php
@@ -32,18 +32,15 @@ class CAttendance extends AbstractResource implements ResourceInterface
     protected $iid;
 
     /**
-     * @var string
      * @Assert\NotBlank
      * @ORM\Column(name="name", type="text", nullable=false)
      */
-    protected $name;
+    protected string $name;
 
     /**
-     * @var string
-     *
      * @ORM\Column(name="description", type="text", nullable=true)
      */
-    protected $description;
+    protected string $description;
 
     /**
      * @var int
@@ -82,6 +79,7 @@ class CAttendance extends AbstractResource implements ResourceInterface
 
     public function __construct()
     {
+        $this->description = '';
         $this->active = 1;
         $this->attendanceQualifyMax = 0;
         $this->locked = 0;
@@ -94,12 +92,8 @@ class CAttendance extends AbstractResource implements ResourceInterface
 
     /**
      * Set name.
-     *
-     * @param string $name
-     *
-     * @return CAttendance
      */
-    public function setName($name)
+    public function setName(string $name): self
     {
         $this->name = $name;
 
@@ -120,10 +114,8 @@ class CAttendance extends AbstractResource implements ResourceInterface
      * Set description.
      *
      * @param string $description
-     *
-     * @return CAttendance
      */
-    public function setDescription($description)
+    public function setDescription($description): self
     {
         $this->description = $description;
 
diff --git a/src/CourseBundle/Entity/CCourseDescription.php b/src/CourseBundle/Entity/CCourseDescription.php
index 4601bbdced..c5137cf706 100644
--- a/src/CourseBundle/Entity/CCourseDescription.php
+++ b/src/CourseBundle/Entity/CCourseDescription.php
@@ -36,13 +36,11 @@ class CCourseDescription extends AbstractResource implements ResourceInterface
     protected $iid;
 
     /**
-     * @var string
-     *
      * @Assert\NotBlank
      *
      * @ORM\Column(name="title", type="text", nullable=true)
      */
-    protected $title;
+    protected string $title;
 
     /**
      * @var string
@@ -65,11 +63,9 @@ class CCourseDescription extends AbstractResource implements ResourceInterface
      */
     protected $progress;
 
-    /**
-     * CCourseDescription constructor.
-     */
     public function __construct()
     {
+        $this->content = '';
         $this->progress = 0;
         $this->descriptionType = 1;
     }
diff --git a/src/CourseBundle/Entity/CCourseSetting.php b/src/CourseBundle/Entity/CCourseSetting.php
index 763e308f6b..bc39648500 100644
--- a/src/CourseBundle/Entity/CCourseSetting.php
+++ b/src/CourseBundle/Entity/CCourseSetting.php
@@ -37,13 +37,11 @@ class CCourseSetting
     protected $cId;
 
     /**
-     * @var string
-     *
      * @Assert\NotBlank()
      *
      * @ORM\Column(name="variable", type="string", length=255, nullable=false)
      */
-    protected $variable;
+    protected string $variable;
 
     /**
      * @var string
diff --git a/src/CourseBundle/Entity/CDocument.php b/src/CourseBundle/Entity/CDocument.php
index 5281374369..7ebaa25fac 100644
--- a/src/CourseBundle/Entity/CDocument.php
+++ b/src/CourseBundle/Entity/CDocument.php
@@ -136,27 +136,25 @@ class CDocument extends AbstractResource implements ResourceInterface
     protected $iid;
 
     /**
-     * @var string
      * @Assert\NotBlank
      * @Groups({"document:read", "document:write"})
      * @ORM\Column(name="title", type="string", length=255, nullable=true)
      */
-    protected $title;
+    protected string $title;
 
     /**
      * @var string
      * @Groups({"document:read", "document:write"})
      * @ORM\Column(name="comment", type="text", nullable=true)
      */
-    protected $comment;
+    protected string $comment;
 
     /**
-     * @var string File type, it can be 'folder' or 'file'
      * @Groups({"document:read", "document:write"})
      * @Assert\Choice({"folder", "file"}, message="Choose a valid filetype.")
      * @ORM\Column(name="filetype", type="string", length=10, nullable=false)
      */
-    protected $filetype;
+    protected string $filetype;
 
     /**
      * @var bool
@@ -175,6 +173,7 @@ class CDocument extends AbstractResource implements ResourceInterface
      */
     public function __construct()
     {
+        $this->comment = '';
         $this->filetype = 'folder';
         $this->readonly = false;
         $this->template = false;
diff --git a/src/CourseBundle/Entity/CForumCategory.php b/src/CourseBundle/Entity/CForumCategory.php
index 9f78ce96ae..9013baec1b 100644
--- a/src/CourseBundle/Entity/CForumCategory.php
+++ b/src/CourseBundle/Entity/CForumCategory.php
@@ -41,20 +41,18 @@ class CForumCategory extends AbstractResource implements ResourceInterface
     protected $cId;
 
     /**
-     * @var string
-     *
      * @Assert\NotBlank()
      *
      * @ORM\Column(name="cat_title", type="string", length=255, nullable=false)
      */
-    protected $catTitle;
+    protected string $catTitle;
 
     /**
      * @var string
      *
      * @ORM\Column(name="cat_comment", type="text", nullable=true)
      */
-    protected $catComment;
+    protected string $catComment;
 
     /**
      * @var int
@@ -93,6 +91,7 @@ class CForumCategory extends AbstractResource implements ResourceInterface
 
     public function __construct()
     {
+        $this->catComment = '';
         $this->locked = 0;
         $this->catId = 0;
         $this->forums = new ArrayCollection();
diff --git a/src/CourseBundle/Entity/CForumThread.php b/src/CourseBundle/Entity/CForumThread.php
index 6b4f264a33..a815acaa93 100644
--- a/src/CourseBundle/Entity/CForumThread.php
+++ b/src/CourseBundle/Entity/CForumThread.php
@@ -42,13 +42,11 @@ class CForumThread extends AbstractResource implements ResourceInterface
     protected $cId;
 
     /**
-     * @var string
-     *
      * @Assert\NotBlank()
      *
      * @ORM\Column(name="thread_title", type="string", length=255, nullable=true)
      */
-    protected $threadTitle;
+    protected string $threadTitle;
 
     /**
      * @var CForumForum|null
@@ -71,7 +69,7 @@ class CForumThread extends AbstractResource implements ResourceInterface
      * @ORM\ManyToOne(targetEntity="Chamilo\CoreBundle\Entity\User")
      * @ORM\JoinColumn(name="thread_poster_id", referencedColumnName="id")
      */
-    protected $user;
+    protected User $user;
 
     /**
      * @var int