diff --git a/API_SQLuedo/API/Controllers/UserController.cs b/API_SQLuedo/API/Controllers/UserController.cs
index 1c1a6d4..5096353 100644
--- a/API_SQLuedo/API/Controllers/UserController.cs
+++ b/API_SQLuedo/API/Controllers/UserController.cs
@@ -179,9 +179,9 @@ namespace API.Controllers
         [ProducesResponseType(typeof(UserDto), 200)]
         [ProducesResponseType(typeof(string), 400)]
         [ProducesResponseType(typeof(string), 404)]
-        public IActionResult UpdateUser(int id, [FromBody] UserDto UserDto)
+        public IActionResult UpdateUser(int id, [FromBody] UserDto userDto)
         {
-            if (id != UserDto.Id)
+            if (id != userDto.Id)
             {
                 logger.LogError("[ERREUR] Problème ID - La mise à jour de l'utilisateur avec l'id {id} a échouée.", id);
                 return BadRequest();
@@ -194,15 +194,17 @@ namespace API.Controllers
                 return BadRequest();
             }
 
-            if (UserDto != null)
+            if (userDto.Username == userService.GetUserById(id).Username && !userService.IsEmailTaken(userDto.Email)
+                || (userDto.Email == userService.GetUserById(id).Email &&
+                    !userService.IsUsernameTaken(userDto.Username))
+                || (!userService.IsEmailTaken(userDto.Email) && !userService.IsUsernameTaken(userDto.Username)))
             {
                 logger.LogInformation("[INFORMATION] La mise à jour de l'utilisateur avec l'id {id} a été effectuée",
                     id);
-                return Ok(userService.UpdateUser(id, UserDto));
+                return Ok(userService.UpdateUser(id, userDto));
             }
-
-            logger.LogError("[ERREUR] Aucun utilisateur trouvé avec l'id {id}.", id);
-            return NotFound();
+            logger.LogError("[ERREUR] Email ou nom d'utilisateur déjà utilisé");
+            return StatusCode(409,"Email ou nom d'utilisateur déjà utilisé");
         }
     }
 }
\ No newline at end of file
diff --git a/API_SQLuedo/TestAPI/UserUnitTest.cs b/API_SQLuedo/TestAPI/UserUnitTest.cs
index abdfbfb..599b33f 100644
--- a/API_SQLuedo/TestAPI/UserUnitTest.cs
+++ b/API_SQLuedo/TestAPI/UserUnitTest.cs
@@ -350,6 +350,106 @@ public class UserUnitTest
             Assert.Equal(400, bdObjectResult.StatusCode);
         }
     }
+    [Fact]
+    public void UpdateUserFailWithExistingUsername()
+    {
+        _userService.Setup(x => x.IsUsernameTaken("Useruser")).Returns(true);
+        _userService.Setup(x => x.IsEmailTaken("heudfk@hdye.com")).Returns(false);
+        _userService.Setup(x => x.GetUserById(1)).Returns(new UserDto(1, "Leuser", "motdepasse", "deuxadresse@gmail.com", true));
+        _userService.Setup(x => x.UpdateUser(1, new UserDto(1, "Useruser", "Passssss", "heudfk@hdye.com", true)))
+            .Returns(new UserDto("Useruser", "Passssss", "heudfk@hdye.com", true));
+
+        var usersController = new UsersController(new NullLogger<UsersController>(), _userService.Object);
+
+        var userResult = usersController.UpdateUser(1, new UserDto(1,"Useruser", "Passssss", "heudfk@hdye.com", true));
+
+        if (userResult is StatusCodeResult statusCodeResult)
+        {
+            Assert.Equal(409, statusCodeResult.StatusCode);
+        }
+    }
+    [Fact]
+    public void UpdateUserFailWithExistingEmail()
+    {
+        _userService.Setup(x => x.IsUsernameTaken("Test1234")).Returns(false);
+        _userService.Setup(x => x.IsEmailTaken("adressemail@gmail.com")).Returns(true);
+        _userService.Setup(x => x.GetUserById(1)).Returns(new UserDto(1, "Leuser", "motdepasse", "deuxadresse@gmail.com", true));
+        _userService.Setup(x => x.UpdateUser(1, new UserDto(1, "Test1234", "Passssss", "adressemail@gmail.com", true)))
+            .Returns(new UserDto("Test1234", "Passssss", "adressemail@gmail.com", true));
+
+        var usersController = new UsersController(new NullLogger<UsersController>(), _userService.Object);
+
+        var userResult = usersController.UpdateUser(1, new UserDto(1,"Test1234", "Passssss", "adressemail@gmail.com", true));
+
+        if (userResult is StatusCodeResult statusCodeResult)
+        {
+            Assert.Equal(409, statusCodeResult.StatusCode);
+        }
+    }
+    [Fact]
+    public void UpdateUserFailWithExistingEmailAndExistingUsername()
+    {
+        _userService.Setup(x => x.IsUsernameTaken("Useruser")).Returns(true);
+        _userService.Setup(x => x.IsEmailTaken("adressemail@gmail.com")).Returns(true);
+        _userService.Setup(x => x.GetUserById(1)).Returns(new UserDto(1, "Leuser", "motdepasse", "deuxadresse@gmail.com", true));
+        _userService.Setup(x => x.UpdateUser(1, new UserDto(1, "Useruser", "Passssss", "adressemail@gmail.com", true)))
+            .Returns(new UserDto("Useruser", "Passssss", "adressemail@gmail.com", true));
+
+        var usersController = new UsersController(new NullLogger<UsersController>(), _userService.Object);
+
+        var userResult = usersController.UpdateUser(1, new UserDto(1,"Useruser", "Passssss", "adressemail@gmail.com", true));
+
+        if (userResult is StatusCodeResult statusCodeResult)
+        {
+            Assert.Equal(409, statusCodeResult.StatusCode);
+        }
+    }
+    [Fact]
+    public void UpdateUserSucessWithSameEmail()
+    {
+        _userService.Setup(x => x.IsUsernameTaken("Test1234")).Returns(false);
+        _userService.Setup(x => x.IsEmailTaken("deuxadresse@gmail.com")).Returns(true);
+        _userService.Setup(x => x.GetUserById(1)).Returns(new UserDto(1, "Leuser", "motdepasse", "deuxadresse@gmail.com", true));
+        _userService.Setup(x => x.UpdateUser(1, new UserDto(1, "Test1234", "Passssss", "deuxadresse@gmail.com", true)))
+            .Returns(new UserDto("Test1234", "Passssss", "deuxadresse@gmail.com", true));
+
+        var usersController = new UsersController(new NullLogger<UsersController>(), _userService.Object);
+
+        var userResult = usersController.UpdateUser(1, new UserDto(1,"Test1234", "Passssss", "deuxadresse@gmail.com", true));
+        if (userResult is OkObjectResult okObjectResult)
+        {
+            UserDto valeur = okObjectResult.Value as UserDto;
+
+            Assert.NotNull(valeur);
+            Assert.Equal("Test1234", valeur.Username);
+            Assert.Equal("Passssss", valeur.Password);
+            Assert.Equal("deuxadresse@gmail.com", valeur.Email);
+            Assert.True(valeur.IsAdmin);
+        }
+    }
+    [Fact]
+    public void UpdateUserSucessWithSameUsername()
+    {
+        _userService.Setup(x => x.IsUsernameTaken("Leuser")).Returns(true);
+        _userService.Setup(x => x.IsEmailTaken("heudfk@hdye.com")).Returns(false);
+        _userService.Setup(x => x.GetUserById(1)).Returns(new UserDto(1, "Leuser", "motdepasse", "deuxadresse@gmail.com", true));
+        _userService.Setup(x => x.UpdateUser(1, new UserDto(1, "Test1234", "Passssss", "heudfk@hdye.com", true)))
+            .Returns(new UserDto("Leuser", "Passssss", "heudfk@hdye.com", true));
+
+        var usersController = new UsersController(new NullLogger<UsersController>(), _userService.Object);
+
+        var userResult = usersController.UpdateUser(1, new UserDto(1,"Leuser", "Passssss", "heudfk@hdye.com", true));
+        if (userResult is OkObjectResult okObjectResult)
+        {
+            UserDto valeur = okObjectResult.Value as UserDto;
+
+            Assert.NotNull(valeur);
+            Assert.Equal("Leuser", valeur.Username);
+            Assert.Equal("Passssss", valeur.Password);
+            Assert.Equal("heudfk@hdye.com", valeur.Email);
+            Assert.True(valeur.IsAdmin);
+        }
+    }
 
     private List<UserDto> GetUsersData()
     {