diff --git a/base/static/css/main.css b/base/static/css/main.css
index 60f2420..e916ab0 100644
--- a/base/static/css/main.css
+++ b/base/static/css/main.css
@@ -64,3 +64,9 @@ article.message {
         color: var(--pico-color-red-500);
     }
 }
+
+.form-error::before  {
+    margin-right: .5em;
+    font-family: remixicon;
+    content: "\eca0";
+}
diff --git a/base/templates/base/form.html b/base/templates/base/form.html
index df40bc7..979daa3 100644
--- a/base/templates/base/form.html
+++ b/base/templates/base/form.html
@@ -1,8 +1,4 @@
-{% if form.non_field_errors %}
-    <ul class="form-errors">
-        {% for error in form.non_field_errors %}<li>{{ error }}</li>{% endfor %}
-    </ul>
-{% endif %}
+{% for error in form.non_field_errors %}<article class="message error">{{ error }}</article>{% endfor %}
 <form method="post" {% if action %}action="{% url action %}"{% endif %}>
     {% csrf_token %}
     <fieldset>
@@ -10,12 +6,10 @@
             <label>
                 {{ field.label }}
                 {{ field }}
+                {% if field.errors %}
+                    <small id="{{ field.errors.field_id }}_error" class="form-error">{{ field.errors|join:", " }}</small>
+                {% endif %}
             </label>
-            {% if field.errors %}
-                <ul class="form-errors">
-                    {% for error in field.errors %}<li>{{ error }}</li>{% endfor %}
-                </ul>
-            {% endif %}
         {% endfor %}
     </fieldset>
     <input type="submit" {% if submit %}value="{{ submit }}"{% endif %}>
diff --git a/game/migrations/0013_alter_group_unique_together_and_more.py b/game/migrations/0013_alter_group_unique_together_and_more.py
new file mode 100644
index 0000000..438a287
--- /dev/null
+++ b/game/migrations/0013_alter_group_unique_together_and_more.py
@@ -0,0 +1,53 @@
+# Generated by Django 5.2.3 on 2025-06-14 08:13
+
+import django.db.models.functions.text
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("game", "0012_alter_musikgame_playlist"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name="group",
+            unique_together=set(),
+        ),
+        migrations.AlterUniqueTogether(
+            name="musicgameorder",
+            unique_together=set(),
+        ),
+        migrations.AlterUniqueTogether(
+            name="musicvideo",
+            unique_together=set(),
+        ),
+        migrations.AddConstraint(
+            model_name="group",
+            constraint=models.UniqueConstraint(
+                django.db.models.functions.text.Lower("name"),
+                models.F("owner"),
+                name="unique_group_name",
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="musicgameorder",
+            constraint=models.UniqueConstraint(
+                fields=("game", "player", "music_video"), name="unique_music_in_game"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="musicgameorder",
+            constraint=models.UniqueConstraint(
+                fields=("game", "order"), name="unique_order"
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="musicvideo",
+            constraint=models.UniqueConstraint(
+                fields=("yt_id", "owner", "group"), name="unique_music_in_group"
+            ),
+        ),
+    ]
diff --git a/game/models.py b/game/models.py
index 8383915..886bd21 100644
--- a/game/models.py
+++ b/game/models.py
@@ -1,5 +1,6 @@
 from django.contrib.auth.models import User
 from django.db import models
+from django.db.models.functions import Lower
 from django.urls import reverse
 
 
@@ -19,7 +20,9 @@ class Group(models.Model):
         return reverse("group_detail", kwargs={"pk": self.pk})
 
     class Meta:
-        unique_together = ["name", "owner"]
+        constraints = [
+            models.UniqueConstraint(Lower("name"), "owner", name="unique_group_name")
+        ]
 
 
 class MusicVideo(models.Model):
@@ -31,7 +34,11 @@ class MusicVideo(models.Model):
     blacklisted = models.BooleanField(default=False)
 
     class Meta:
-        unique_together = ["yt_id", "owner", "group"]
+        constraints = [
+            models.UniqueConstraint(
+                fields=("yt_id", "owner", "group"), name="unique_music_in_group"
+            )
+        ]
 
 
 class MusikGame(models.Model):
@@ -52,5 +59,10 @@ class MusicGameOrder(models.Model):
     order = models.PositiveIntegerField()
 
     class Meta:
-        unique_together = [["game", "player", "music_video"], ["game", "order"]]
+        constraints = [
+            models.UniqueConstraint(
+                fields=("game", "player", "music_video"), name="unique_music_in_game"
+            ),
+            models.UniqueConstraint(fields=("game", "order"), name="unique_order"),
+        ]
         ordering = ["order"]
diff --git a/game/views.py b/game/views.py
index 1b188e5..0c0dad3 100644
--- a/game/views.py
+++ b/game/views.py
@@ -7,6 +7,7 @@ from django.conf import settings
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib.auth.models import User
 from django.contrib.messages.views import SuccessMessageMixin
+from django.db import IntegrityError
 from django.db.models import Count, Q
 from django.http import JsonResponse
 from django.shortcuts import get_object_or_404, redirect
@@ -40,7 +41,11 @@ class GroupMixin:
 class GroupCreateView(LoginRequiredMixin, GroupMixin, CreateView):
     def form_valid(self, form):
         form.instance.owner = self.request.user
-        return super().form_valid(form)
+        try:
+            return super().form_valid(form)
+        except IntegrityError:
+            form.add_error("name", "Ce nom de groupe existe déjà.")
+            return super().form_invalid(form)
 
 
 class GroupUpdateView(OwnerFilterMixin, GroupMixin, UpdateView):