diff --git a/wsmaster/che-core-api-user/src/main/java/org/eclipse/che/api/user/server/UserManager.java b/wsmaster/che-core-api-user/src/main/java/org/eclipse/che/api/user/server/UserManager.java
index 54cc273d65f..6f1da2d75b5 100644
--- a/wsmaster/che-core-api-user/src/main/java/org/eclipse/che/api/user/server/UserManager.java
+++ b/wsmaster/che-core-api-user/src/main/java/org/eclipse/che/api/user/server/UserManager.java
@@ -10,6 +10,8 @@
  *******************************************************************************/
 package org.eclipse.che.api.user.server;
 
+import com.google.common.collect.Sets;
+
 import org.eclipse.che.api.core.ConflictException;
 import org.eclipse.che.api.core.NotFoundException;
 import org.eclipse.che.api.core.ServerException;
@@ -22,9 +24,11 @@
 import org.slf4j.LoggerFactory;
 
 import javax.inject.Inject;
+import javax.inject.Named;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Set;
 
 import static com.google.common.base.MoreObjects.firstNonNull;
 import static java.lang.String.format;
@@ -45,15 +49,17 @@ public class UserManager {
     private final UserDao        userDao;
     private final UserProfileDao profileDao;
     private final PreferenceDao  preferenceDao;
-
+    private final Set<String>    reservedNames;
 
     @Inject
     public UserManager(UserDao userDao,
                        UserProfileDao profileDao,
-                       PreferenceDao preferenceDao) {
+                       PreferenceDao preferenceDao,
+                       @Named("user.reserved_names") String[] reservedNames) {
         this.userDao = userDao;
         this.profileDao = profileDao;
         this.preferenceDao = preferenceDao;
+        this.reservedNames = Sets.newHashSet(reservedNames);
     }
 
 
@@ -68,6 +74,9 @@ public UserManager(UserDao userDao,
      *         when any other error occurs
      */
     public void create(User user, boolean isTemporary) throws ConflictException, ServerException {
+        if (reservedNames.contains(user.getName().toLowerCase())) {
+            throw new ConflictException(String.format("Username \"%s\" is reserved", user.getName()));
+        }
         user.withId(generate("user", ID_LENGTH))
             .withPassword(firstNonNull(user.getPassword(), generate("", PASSWORD_LENGTH)));
         userDao.create(user);
diff --git a/wsmaster/che-core-api-user/src/test/java/org/eclipse/che/api/user/server/UserManagerTest.java b/wsmaster/che-core-api-user/src/test/java/org/eclipse/che/api/user/server/UserManagerTest.java
index 81262fbc1af..a6769e8880a 100644
--- a/wsmaster/che-core-api-user/src/test/java/org/eclipse/che/api/user/server/UserManagerTest.java
+++ b/wsmaster/che-core-api-user/src/test/java/org/eclipse/che/api/user/server/UserManagerTest.java
@@ -10,15 +10,15 @@
  *******************************************************************************/
 package org.eclipse.che.api.user.server;
 
-import org.eclipse.che.api.core.BadRequestException;
+import org.eclipse.che.api.core.ConflictException;
 import org.eclipse.che.api.user.server.dao.PreferenceDao;
 import org.eclipse.che.api.user.server.dao.Profile;
 import org.eclipse.che.api.user.server.dao.User;
 import org.eclipse.che.api.user.server.dao.UserDao;
 import org.eclipse.che.api.user.server.dao.UserProfileDao;
-import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.testng.MockitoTestNGListener;
+import org.testng.annotations.BeforeMethod;
 import org.testng.annotations.Listeners;
 import org.testng.annotations.Test;
 
@@ -26,7 +26,6 @@
 import static org.mockito.Matchers.anyMapOf;
 import static org.mockito.Matchers.anyString;
 import static org.mockito.Matchers.eq;
-import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 
 /**
@@ -45,12 +44,17 @@ public class UserManagerTest {
     @Mock
     PreferenceDao  preferenceDao;
 
-    @InjectMocks
     UserManager manager;
 
+    @BeforeMethod
+    public void setUp() {
+        manager = new UserManager(userDao, profileDao, preferenceDao, new String[0]);
+    }
+
     @Test
     public void shouldCreateProfileAndPreferencesOnUserCreation() throws Exception {
         final User user = new User().withEmail("test@email.com").withName("testName");
+
         manager.create(user, false);
 
         verify(profileDao).create(any(Profile.class));
@@ -60,8 +64,16 @@ public void shouldCreateProfileAndPreferencesOnUserCreation() throws Exception {
     @Test
     public void shouldGeneratedPasswordWhenCreatingUserAndItIsMissing() throws Exception {
         final User user = new User().withEmail("test@email.com").withName("testName");
+
         manager.create(user, false);
 
         verify(userDao).create(eq(user.withPassword("<none>")));
     }
+
+    @Test(expectedExceptions = ConflictException.class)
+    public void shouldThrowConflictExceptionOnCreationIfUserNameIsReserved() throws Exception {
+        final User user = new User().withEmail("test@email.com").withName("reserved");
+
+        new UserManager(userDao, profileDao, preferenceDao, new String[] {"reserved"}).create(user, false);
+    }
 }