diff --git a/support-portal-backend/src/main/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceImpl.java b/support-portal-backend/src/main/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceImpl.java
index 5311ead..9fd4dde 100644
--- a/support-portal-backend/src/main/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceImpl.java
+++ b/support-portal-backend/src/main/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceImpl.java
@@ -28,6 +28,12 @@ import java.util.UUID;
 @RequiredArgsConstructor
 public class UserServiceImpl implements UserService {
 
+    public static final String DEFAULT_USER_IMG_PATH = "/user/image/profile/temp";
+    public static final String USERNAME_NOT_FOUND_MSG = "User with username `%s` not found";
+    public static final String USERNAME_EXISTS_MSG = "Username `%s` is already taken. Please select another one";
+    public static final String EMAIL_NOT_FOUND_MSG = "User with email `%s` not found";
+    public static final String EMAIL_EXISTS_MSG = "User with email `%s` is already registered";
+
     private final UserRepository userRepository;
     private final PasswordEncoder passwordEncoder;
 
@@ -36,7 +42,7 @@ public class UserServiceImpl implements UserService {
     public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
         User user = userRepository
                 .findByUsername(username)
-                .orElseThrow(() -> new UsernameNotFoundException("User with username `" + username + "` not found"));
+                .orElseThrow(() -> new UserNotFoundException(String.format(USERNAME_NOT_FOUND_MSG, username)));
         user.setLastLoginDateDisplay(user.getLastLoginDate());
         user.setLastLoginDate(LocalDateTime.now());
         return new UserPrincipal(user);
@@ -73,7 +79,7 @@ public class UserServiceImpl implements UserService {
     }
 
     private String getTemporaryProfileImageUrl() {
-        return ServletUriComponentsBuilder.fromCurrentContextPath().path("/user/image/profile/temp").build().toString();
+        return ServletUriComponentsBuilder.fromCurrentContextPath().path(DEFAULT_USER_IMG_PATH).build().toString();
     }
 
     private String generatePassword() {
@@ -93,14 +99,14 @@ public class UserServiceImpl implements UserService {
     public User findByUsername(String username) {
         return userRepository
                 .findByUsername(username)
-                .orElseThrow(() -> new UserNotFoundException("User with username `" + username + "` not found"));
+                .orElseThrow(() -> new UserNotFoundException(String.format(USERNAME_NOT_FOUND_MSG, username)));
     }
 
     @Override
     public User findByEmail(String email) {
         return userRepository
                 .findByEmail(email)
-                .orElseThrow(() -> new EmailNotFoundException("User with email `" + email + "` not found"));
+                .orElseThrow(() -> new EmailNotFoundException(String.format(EMAIL_NOT_FOUND_MSG, email)));
     }
 
     private void validateNewUsernameAndEmail(String username, String email) {
diff --git a/support-portal-backend/src/test/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceTest.java b/support-portal-backend/src/test/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceTest.java
index 2789a9b..16d7ecd 100644
--- a/support-portal-backend/src/test/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceTest.java
+++ b/support-portal-backend/src/test/java/net/shyshkin/study/fullstack/supportportal/backend/service/UserServiceTest.java
@@ -3,11 +3,11 @@ package net.shyshkin.study.fullstack.supportportal.backend.service;
 import lombok.extern.slf4j.Slf4j;
 import net.shyshkin.study.fullstack.supportportal.backend.common.BaseUserTest;
 import net.shyshkin.study.fullstack.supportportal.backend.domain.User;
+import net.shyshkin.study.fullstack.supportportal.backend.exception.domain.UserNotFoundException;
 import org.assertj.core.api.ThrowableAssert;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.core.userdetails.UserDetails;
-import org.springframework.security.core.userdetails.UsernameNotFoundException;
 
 import java.time.temporal.ChronoUnit;
 import java.util.Optional;
@@ -58,7 +58,7 @@ class UserServiceTest extends BaseUserTest {
 
         //then
         assertThatThrownBy(execution)
-                .isInstanceOf(UsernameNotFoundException.class)
+                .isInstanceOf(UserNotFoundException.class)
                 .hasMessage("User with username `" + username + "` not found");
     }
 }
\ No newline at end of file