diff --git a/Project/php/controller/TeacherController.php b/Project/php/controller/TeacherController.php
index f92aaf6..68b520e 100755
--- a/Project/php/controller/TeacherController.php
+++ b/Project/php/controller/TeacherController.php
@@ -26,7 +26,7 @@ class TeacherController extends UserController
         $mdl->removeVocById($id);
         $this->affAllVocab();
     }
-    public function getContent(){
+    public function getContent():void{
         global $twig;
         global $user;
         $mdl = new MdlTeacher();
diff --git a/Project/php/gateway/GroupGateway.php b/Project/php/gateway/GroupGateway.php
index 9f15b1f..16a03ba 100755
--- a/Project/php/gateway/GroupGateway.php
+++ b/Project/php/gateway/GroupGateway.php
@@ -65,7 +65,7 @@ class GroupGateway extends AbsGateway
         }
     }
 
-    public function findById(int $id)
+    public function findById(int $id):array
     {
         try{
             $query = "SELECT * FROM Group_ WHERE id = :id";
diff --git a/Project/php/gateway/TranslationGateway.php b/Project/php/gateway/TranslationGateway.php
index da457ec..5ccf88b 100755
--- a/Project/php/gateway/TranslationGateway.php
+++ b/Project/php/gateway/TranslationGateway.php
@@ -64,7 +64,7 @@ class TranslationGateway extends AbsGateway
         }
     }
 
-    public function findById(int $id)
+    public function findById(int $id): array
     {
         try {
             $query = "SELECT * FROM Translate WHERE id=:id";
diff --git a/Project/php/gateway/UserGateway.php b/Project/php/gateway/UserGateway.php
index 808ecc3..2f93662 100755
--- a/Project/php/gateway/UserGateway.php
+++ b/Project/php/gateway/UserGateway.php
@@ -118,7 +118,7 @@ class UserGateway extends AbsGateway
         }
     }
 
-    public function findById(int $id)
+    public function findById(int $id): ?User
     {
         try {
             $query = "SELECT * FROM User_ WHERE id=:id";
@@ -160,7 +160,7 @@ class UserGateway extends AbsGateway
         }
     }
 
-    public function findUserByEmail(string $email): User{
+    public function findUserByEmail(string $email): ?User{
         try {
             $query = "SELECT * FROM User_ WHERE email=:email";
             $args = array(':email' => array($email, PDO::PARAM_STR));
diff --git a/Project/php/gateway/VocabularyListGateway.php b/Project/php/gateway/VocabularyListGateway.php
index be77b7c..91cb090 100755
--- a/Project/php/gateway/VocabularyListGateway.php
+++ b/Project/php/gateway/VocabularyListGateway.php
@@ -67,7 +67,7 @@ class VocabularyListGateway extends AbsGateway
         }
     }
 
-    public function findById(int $id)
+    public function findById(int $id) : ?VocabularyList
     {
         try{
             $query = "SELECT * FROM VocabularyList WHERE id = :id";
diff --git a/Project/php/model/AbsModel.php b/Project/php/model/AbsModel.php
index 6cbc3eb..1694975 100755
--- a/Project/php/model/AbsModel.php
+++ b/Project/php/model/AbsModel.php
@@ -6,7 +6,7 @@ use gateway\UserGateway;
 
 abstract class AbsModel
 {
-    public function connection(string $login, string $password){
+    public function connection(string $login, string $password):?User{
         $gtw = new UserGateway();
         $hash = $gtw->login($login) ?? null;
 
@@ -24,7 +24,7 @@ abstract class AbsModel
         return null;
     }
 
-    public function deconnection(){
+    public function deconnection():void{
         session_unset();
         session_destroy();
         $_SESSION = array();
@@ -35,5 +35,5 @@ abstract class AbsModel
         return $gtw->findUserByEmail($login) != null;
     }
 
-    public abstract function is(string $login, array $roles): User;
+    public abstract function is(string $login, array $roles): ?User;
 }
\ No newline at end of file
diff --git a/Project/php/model/MdlAdmin.php b/Project/php/model/MdlAdmin.php
index 9998c51..bf1754a 100755
--- a/Project/php/model/MdlAdmin.php
+++ b/Project/php/model/MdlAdmin.php
@@ -67,7 +67,7 @@ class MdlAdmin extends MdlUser
         return $gtw->findUnassignedUsers();
     }
 
-    public function is(string $login, array $roles): User
+    public function is(string $login, array $roles): ?User
     {
         $gtw = new UserGateway();
         $user = $gtw->findUserByEmail($login);
diff --git a/Project/php/model/MdlStudent.php b/Project/php/model/MdlStudent.php
index fc96b52..fc113be 100755
--- a/Project/php/model/MdlStudent.php
+++ b/Project/php/model/MdlStudent.php
@@ -19,7 +19,7 @@ class MdlStudent extends MdlUser
         return $res;
     }
 
-    public function is(string $login, array $roles): User
+    public function is(string $login, array $roles): ?User
     {
         $gtw = new UserGateway();
         $user = $gtw->findUserByEmail($login);
diff --git a/Project/php/model/MdlTeacher.php b/Project/php/model/MdlTeacher.php
index 3a733b1..2ca23cc 100755
--- a/Project/php/model/MdlTeacher.php
+++ b/Project/php/model/MdlTeacher.php
@@ -76,7 +76,7 @@ class MdlTeacher extends MdlUser
         }
     }
 
-    public function is(string $login, array $roles): User
+    public function is(string $login, array $roles): ?User
     {
         $gtw = new UserGateway();
         $user = $gtw->findUserByEmail($login);
diff --git a/Project/php/model/MdlUser.php b/Project/php/model/MdlUser.php
index cfed1bc..bc1e7a6 100755
--- a/Project/php/model/MdlUser.php
+++ b/Project/php/model/MdlUser.php
@@ -16,7 +16,7 @@ class MdlUser extends AbsModel {
         $gtw->modifyPassword($id, $newPassword);
     }
 
-    public function is(string $login, array $roles): User
+    public function is(string $login, array $roles): ?User
     {
         $gtw = new UserGateway();
         $user = $gtw->findUserByEmail($login);