diff --git a/account_manager/views/user_views.py b/account_manager/views/user_views.py
index c53d4ba..94a9ff5 100644
--- a/account_manager/views/user_views.py
+++ b/account_manager/views/user_views.py
@@ -4,7 +4,7 @@ from django.contrib.auth.views import PasswordResetConfirmView, PasswordChangeVi
 from django.contrib.sites.shortcuts import get_current_site
 from django.core.exceptions import ObjectDoesNotExist
 from django.shortcuts import render, redirect
-
+from ldap import ALREADY_EXISTS
 from account_helper.models import Realm
 from account_manager.forms import AddLDAPUserForm, UserDeleteListForm, UpdateLDAPUserForm, AdminUpdateLDAPUserForm, \
     UserGroupListForm
@@ -53,19 +53,23 @@ def user_add(request, realm_id):
             if request.is_secure():
                 protocol = 'https'
             LdapUser.base_dn = f'ou=people,{realm.ldap_base_dn}'
-            LdapUser.create_with_django_user_creation_and_welcome_mail(realm=realm,
-                                                                       protocol=protocol,
-                                                                       domain=current_site.domain,
-                                                                       username=username,
-                                                                       email=email)
-            user = LdapUser.objects.get(username=username)
-            LdapGroup.base_dn = f'ou=groups,{realm.ldap_base_dn}'
-            default_ldap_group = LdapGroup.objects.get(name=realm.default_group.name)
-            if default_ldap_group:
-                ldap_add_user_to_groups(ldap_user=user.dn, user_groups=[default_ldap_group, ])
-            return redirect('realm-user-list', realm_id)
+            try:
+                LdapUser.create_with_django_user_creation_and_welcome_mail(realm=realm,
+                                                                           protocol=protocol,
+                                                                           domain=current_site.domain,
+                                                                           username=username,
+                                                                           email=email)
+                if realm.default_group:
+                    user = LdapUser.objects.get(username=username)
 
-    # if a GET (or any other method) we'll create a blank form
+                    LdapGroup.base_dn = f'ou=groups,{realm.ldap_base_dn}'
+                    default_ldap_group = LdapGroup.objects.get(name=realm.default_group.name)
+                    ldap_add_user_to_groups(ldap_user=user.dn, user_groups=[default_ldap_group, ])
+
+                return redirect('realm-user-list', realm_id)
+            except ALREADY_EXISTS as err:
+                return render(request, 'user/realm_user_add.jinja2', {'form': form, 'realm': realm,
+                                                                      'extra_error': f'Nutzer {username} existiert bereits.'})
     else:
         form = AddLDAPUserForm()
     return render(request, 'user/realm_user_add.jinja2', {'form': form, 'realm': realm})
diff --git a/templates/user/realm_user_add.jinja2 b/templates/user/realm_user_add.jinja2
index 31c97a8..6a3bc8d 100644
--- a/templates/user/realm_user_add.jinja2
+++ b/templates/user/realm_user_add.jinja2
@@ -3,9 +3,12 @@
 
 {% block detail_content %}
     <h2>Nutzer anlegen</h2>
+    {% if extra_error %}
+        <div class="alert alert-warning">{{ extra_error }}</div>
+    {% endif %}
     <form action="{{ url('realm-user-add', args=[realm.id]) }}" method="post">
         <input type="hidden" name="csrfmiddlewaretoken" value="{{ csrf_token }}">
-{#        {{ form.as_p() }}#}
+        {#        {{ form.as_p() }}#}
         {{ mform.text_input(form.username) }}
         {{ mform.email_input(form.email) }}
         <div class="d-flex mt-4">