diff --git a/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java b/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
index 0b57ea8..6774cd9 100644
--- a/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
+++ b/src/Client/src/main/java/greenify/client/controller/RegisterWindowController.java
@@ -30,6 +30,7 @@ import javafx.stage.Window;
 import javafx.util.Duration;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
+import org.springframework.web.client.HttpClientErrorException;
 
 import java.io.IOException;
 import java.text.DecimalFormat;
@@ -221,7 +222,7 @@ public class RegisterWindowController {
         //register the user with the provided username and password
         try {
             userService.registerUser(userNameText.getText(), passwordField.getText());
-        } catch (Exception ex) {
+        } catch (HttpClientErrorException ex) {
             UserController.AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Username Error!",
                     "This username has already been taken!");
             return;
diff --git a/src/Client/src/main/java/greenify/client/controller/UserController.java b/src/Client/src/main/java/greenify/client/controller/UserController.java
index 89160be..3c27973 100644
--- a/src/Client/src/main/java/greenify/client/controller/UserController.java
+++ b/src/Client/src/main/java/greenify/client/controller/UserController.java
@@ -2,6 +2,7 @@ package greenify.client.controller;
 
 import greenify.client.Application;
 import greenify.client.rest.UserService;
+import greenify.common.ApplicationException;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.Parent;
@@ -14,6 +15,7 @@ import javafx.stage.Stage;
 import javafx.stage.Window;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
+import org.springframework.web.client.HttpClientErrorException;
 
 import java.io.IOException;
 import java.util.Objects;
@@ -67,7 +69,7 @@ public class UserController {
         //log the user in with the userService method
         try {
             userService.loginUser(usernameField.getText(), passwordField.getText());
-        } catch (RuntimeException ex) {
+        } catch (HttpClientErrorException ex) {
             AlertHelper.showAlert(Alert.AlertType.ERROR, owner, "Log-in Error!",
                     "Your username or password is incorrect!");
             return;