diff --git a/accessData/src/main/kotlin/com/intelligentbackpack/accessdata/datasource/AccessDomainRepositoryImpl.kt b/accessData/src/main/kotlin/com/intelligentbackpack/accessdata/datasource/AccessDomainRepositoryImpl.kt
index d0ee8a7a..969b0826 100644
--- a/accessData/src/main/kotlin/com/intelligentbackpack/accessdata/datasource/AccessDomainRepositoryImpl.kt
+++ b/accessData/src/main/kotlin/com/intelligentbackpack/accessdata/datasource/AccessDomainRepositoryImpl.kt
@@ -15,66 +15,110 @@ class AccessDomainRepositoryImpl(
 
     /**
      * Creates a new user.
+     *
      * @param user is the user to create.
-     * @return the created user.
-     * @throws Exception if the user cannot be created.
+     * @param success is the success callback.
+     * @param error is the error callback.
      *
      * The user is created in the remote data storage and then saved in the local data storage.
      */
-    override fun createUser(user: User): User =
-        accessRemoteDataStorage.createUser(user)
-            .also { accessLocalDataStorage.saveUser(it) }
+    override fun createUser(user: User, success: (User) -> Unit, error: (Exception) -> Unit) {
+        try {
+            success(
+                accessRemoteDataStorage.createUser(user)
+                    .also { accessLocalDataStorage.saveUser(it) }
+            )
+        } catch (e: Exception) {
+            error(e)
+        }
+    }
+
 
     /**
      * Checks if a user is logged.
-     * @return true if the user is logged, false otherwise.
+     *
+     * @param success is the success callback with true if the user is logged, false otherwise.
+     * @param error is the error callback.
      *
      * The user is checked in the local data storage.
      */
-    override fun isUserLogged(): Boolean = accessLocalDataStorage.isUserSaved()
+    override fun isUserLogged(success: (Boolean) -> Unit, error: (Exception) -> Unit) {
+        try {
+            success(accessLocalDataStorage.isUserSaved())
+        } catch (e: Exception) {
+            error(e)
+        }
+    }
 
     /**
      * Logs a user using email and password.
+     *
      * @param email is the user email.
      * @param password is the user password.
-     * @return the logged user.
-     * @throws Exception if the user cannot be logged.
+     * @param success is the success callback with the logged user.
+     * @param error is the error callback.
      *
      * The user is logged in the remote data storage and then saved in the local data storage.
      */
-    override fun loginWithData(email: String, password: String): User =
-        accessRemoteDataStorage
-            .accessWithData(email, password)
-            .also { accessLocalDataStorage.saveUser(it) }
+    override fun loginWithData(email: String, password: String, success: (User) -> Unit, error: (Exception) -> Unit) {
+        try {
+            success(
+                accessRemoteDataStorage.accessWithData(email, password)
+                    .also { accessLocalDataStorage.saveUser(it) }
+            )
+        } catch (e: Exception) {
+            error(e)
+        }
+    }
 
     /**
      * Logs the saved user.
-     * @return the logged user.
-     * @throws Exception if the user cannot be logged.
+     *
+     * @param success is the success callback with the logged user.
+     * @param error is the error callback.
      *
      * The user is logged in the remote data storage.
      */
-    override fun automaticLogin(): User =
-        accessLocalDataStorage.getUser()
+    override fun automaticLogin(success: (User) -> Unit, error: (Exception) -> Unit) {
+        try {
+            success(accessLocalDataStorage.getUser())
+        } catch (e: Exception) {
+            error(e)
+        }
+    }
 
     /**
      * Logs out the user.
-     * @throws Exception if the user cannot be logged out.
+     *
+     * @param success is the success callback with the logged out user.
+     * @param error is the error callback.
      *
      * The user is deleted in the local data storage.
      */
-    override fun logoutUser() =
-        accessLocalDataStorage.deleteUser()
+    override fun logoutUser(success: (User) -> Unit, error: (Exception) -> Unit) {
+        try {
+            success(accessLocalDataStorage.getUser())
+        } catch (e: Exception) {
+            error(e)
+        }
+    }
 
     /**
      * Deletes the user.
-     * @throws Exception if the user cannot be deleted.
+     *
+     * @param success is the success callback with the deleted user.
+     * @param error is the error callback.
      *
      * The user is deleted in the remote data storage and then in the local data storage.
      */
-    override fun deleteUser() {
-        accessRemoteDataStorage.deleteUser(accessLocalDataStorage.getUser())
-        accessLocalDataStorage.deleteUser()
+    override fun deleteUser(success: (User) -> Unit, error: (Exception) -> Unit) {
+        try {
+            val user = accessLocalDataStorage.getUser()
+            accessRemoteDataStorage.deleteUser(user)
+            accessLocalDataStorage.deleteUser()
+            success(user)
+        } catch (e: Exception) {
+            error(e)
+        }
     }
-
-}
\ No newline at end of file
+}
diff --git a/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/repository/AccessDomainRepository.kt b/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/repository/AccessDomainRepository.kt
index ed1c3db4..23dc9fb3 100644
--- a/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/repository/AccessDomainRepository.kt
+++ b/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/repository/AccessDomainRepository.kt
@@ -9,38 +9,52 @@ interface AccessDomainRepository {
 
     /**
      * Creates a new user.
+     *
      * @param user is the user to create.
-     * @return the created user.
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun createUser(user: User): User
+    fun createUser(user: User, success: (User) -> Unit, error: (Exception) -> Unit)
 
     /**
      * Checks if a user is logged.
-     * @return true if the user is logged, false otherwise.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun isUserLogged(): Boolean
+    fun isUserLogged(success: (Boolean) -> Unit, error: (Exception) -> Unit)
 
     /**
      * Logs a user using email and password.
+     *
      * @param email is the user email.
      * @param password is the user password.
-     * @return the logged user.
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun loginWithData(email: String, password: String): User
+    fun loginWithData(email: String, password: String, success: (User) -> Unit, error: (Exception) -> Unit)
 
     /**
      * Logs the saved user.
-     * @return the logged user.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun automaticLogin(): User
+    fun automaticLogin(success: (User) -> Unit, error: (Exception) -> Unit)
 
     /**
      * Logs out the user.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun logoutUser()
+    fun logoutUser(success: (User) -> Unit, error: (Exception) -> Unit)
 
     /**
      * Deletes the user.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    fun deleteUser()
+    fun deleteUser(success: (User) -> Unit, error: (Exception) -> Unit)
 }
diff --git a/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/usecase/AccessUseCase.kt b/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/usecase/AccessUseCase.kt
index d6416729..ee2a20fa 100644
--- a/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/usecase/AccessUseCase.kt
+++ b/accessDomain/src/main/kotlin/com/intelligentbackpack/accessdomain/usecase/AccessUseCase.kt
@@ -12,37 +12,54 @@ class AccessUseCase(private val repository: AccessDomainRepository) {
     /**
      * Creates a new user.
      * @param user is the user to create.
-     * @return the created user.
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    suspend fun createUser(user: User) = repository.createUser(user)
+    suspend fun createUser(user: User, success: (User) -> Unit, error: (Exception) -> Unit) =
+        repository.createUser(user, success, error)
 
     /**
      * Checks if a user is logged.
-     * @return true if the user is logged, false otherwise.
+     *
+     * @param success is the success callback with true if the user is logged, false otherwise.
+     * @param error is the error callback.
      */
-    suspend fun isUserLogged() = repository.isUserLogged()
+    suspend fun isUserLogged(success: (Boolean) -> Unit, error: (Exception) -> Unit) =
+        repository.isUserLogged(success, error)
 
     /**
      * Logs a user using email and password.
+     *
      * @param email is the user email.
      * @param password is the user password.
-     * @return the logged user.
+     * @param success is the success callback with the logged user.
+     * @param error is the error callback.
      */
-    suspend fun loginWithData(email: String, password: String) = repository.loginWithData(email, password)
+    suspend fun loginWithData(email: String, password: String, success: (User) -> Unit, error: (Exception) -> Unit) =
+        repository.loginWithData(email, password, success, error)
 
     /**
      * Logs the saved user.
-     * @return the logged user.
+     *
+     * @param success is the success callback with the logged user.
+     * @param error is the error callback.
      */
-    suspend fun automaticLogin() = repository.automaticLogin()
+    suspend fun automaticLogin(success: (User) -> Unit, error: (Exception) -> Unit) =
+        repository.automaticLogin(success, error)
 
     /**
      * Logs out the user.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    suspend fun logoutUser() = repository.logoutUser()
+    suspend fun logoutUser(success: (User) -> Unit, error: (Exception) -> Unit) = repository.logoutUser(success, error)
 
     /**
      * Deletes the user.
+     *
+     * @param success is the success callback.
+     * @param error is the error callback.
      */
-    suspend fun deleteUser() = repository.deleteUser()
+    suspend fun deleteUser(success: (User) -> Unit, error: (Exception) -> Unit) = repository.deleteUser(success, error)
 }
diff --git a/app/src/main/kotlin/com/intelligentbackpack/app/viewmodel/LoginViewModel.kt b/app/src/main/kotlin/com/intelligentbackpack/app/viewmodel/LoginViewModel.kt
index 3d9817fb..5e251e35 100644
--- a/app/src/main/kotlin/com/intelligentbackpack/app/viewmodel/LoginViewModel.kt
+++ b/app/src/main/kotlin/com/intelligentbackpack/app/viewmodel/LoginViewModel.kt
@@ -31,13 +31,13 @@ class LoginViewModel(
         error: (error: String) -> Unit
     ) {
         viewModelScope.launch {
-            try {
-                withContext(Dispatchers.IO) {
-                    userImpl.postValue(accessUseCase.loginWithData(email, password))
-                }
-                success(userImpl.value!!)
-            } catch (e: Exception) {
-                error(e.message ?: "Unknown error")
+            withContext(Dispatchers.IO) {
+                accessUseCase.loginWithData(email, password, {
+                    userImpl.postValue(it)
+                    success(it)
+                }, {
+                    error(it.message ?: "Unknown error")
+                })
             }
         }
     }
@@ -46,12 +46,20 @@ class LoginViewModel(
         success: (user: User) -> Unit,
     ) {
         viewModelScope.launch {
-            if (accessUseCase.isUserLogged()) {
-                withContext(Dispatchers.IO) {
-                    userImpl.postValue(accessUseCase.automaticLogin())
+            accessUseCase.isUserLogged({ logged ->
+                if (logged) {
+                    viewModelScope.launch {
+                        withContext(Dispatchers.IO) {
+                            accessUseCase.automaticLogin({
+                                userImpl.postValue(it)
+                                success(it)
+                            }, {
+                            })
+                        }
+                    }
                 }
-                success(userImpl.value!!)
-            }
+            }, {
+            })
         }
     }
 
@@ -61,41 +69,46 @@ class LoginViewModel(
         error: (error: String) -> Unit
     ) {
         viewModelScope.launch {
-            try {
-                withContext(Dispatchers.IO) {
-                    userImpl.postValue(accessUseCase.createUser(
-                        User.build {
-                            email = data.email
-                            password = data.password
-                            name = data.name
-                            surname = data.surname
-                        }
-                    ))
-                }
-                success(userImpl.value!!)
-            } catch (e: Exception) {
-                error(e.message ?: "Unknown error")
+            withContext(Dispatchers.IO) {
+                accessUseCase.createUser(
+                    User.build {
+                        email = data.email
+                        password = data.password
+                        name = data.name
+                        surname = data.surname
+                    }, {
+                        userImpl.postValue(it)
+                        success(it)
+                    }, {
+                        error(it.message ?: "Unknown error")
+                    }
+                )
             }
         }
     }
 
+
     fun logout(success: () -> Unit) {
         viewModelScope.launch {
             withContext(Dispatchers.IO) {
-                accessUseCase.logoutUser()
+                accessUseCase.logoutUser({
+                    userImpl.postValue(null)
+                    success()
+                }, {
+                })
             }
-            userImpl.postValue(null)
-            success()
         }
     }
 
     fun deleteUser(success: () -> Unit) {
         viewModelScope.launch {
             withContext(Dispatchers.IO) {
-                accessUseCase.deleteUser()
+                accessUseCase.deleteUser({
+                    userImpl.postValue(null)
+                    success()
+                }, {
+                })
             }
-            userImpl.postValue(null)
-            success()
         }
     }