diff --git a/client/src/components/learningMentor/MyMentors.vue b/client/src/components/learningMentor/MyMentors.vue
index d614348f..4f58c330 100644
--- a/client/src/components/learningMentor/MyMentors.vue
+++ b/client/src/components/learningMentor/MyMentors.vue
@@ -3,6 +3,7 @@ import { useCurrentCourseSession } from "@/composables";
 import ItModal from "@/components/ui/ItModal.vue";
 import { computed, ref } from "vue";
 import { useCSRFFetch } from "@/fetchHelpers";
+import { useUserStore } from "@/stores/user";
 
 const courseSession = useCurrentCourseSession();
 
@@ -33,6 +34,12 @@ const hasMentors = computed(() => {
 });
 
 const validEmail = computed(() => {
+  const isSelfInvitation = Boolean(inviteeEmail.value === useUserStore().email);
+
+  if (isSelfInvitation) {
+    return false;
+  }
+
   const emailRegex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
   return emailRegex.test(inviteeEmail.value);
 });
@@ -81,7 +88,7 @@ const inviteMentor = async () => {
           <div
             v-for="invitation in invitations"
             :key="invitation.id"
-            class="flex flex-col justify-between gap-4 border-b py-2 md:flex-row md:gap-16"
+            class="flex flex-col justify-between gap-4 border-b py-2 last:border-b-0 md:flex-row md:gap-16"
           >
             <div class="flex flex-col md:flex-grow md:flex-row">
               <div class="flex items-center space-x-2">
diff --git a/client/src/pages/learningMentor/InvitationAcceptPage.vue b/client/src/pages/learningMentor/InvitationAcceptPage.vue
index 163712ed..36f3e55b 100644
--- a/client/src/pages/learningMentor/InvitationAcceptPage.vue
+++ b/client/src/pages/learningMentor/InvitationAcceptPage.vue
@@ -1,6 +1,6 @@
 <script setup lang="ts">
 import { useCSRFFetch } from "@/fetchHelpers";
-import { getCockpitUrl } from "@/utils/utils";
+import { getLearningMentorUrl } from "@/utils/utils";
 
 const props = defineProps<{
   courseId: string;
@@ -56,8 +56,8 @@ const { data, error } = useCSRFFetch(
               </template>
             </i18next>
             <div class="mt-4">
-              <a class="underline" :href="getCockpitUrl(data.course_slug)">
-                {{ $t("a.Cockpit anschauen") }}
+              <a class="underline" :href="getLearningMentorUrl(data.course_slug)">
+                {{ $t("a.Übersicht anschauen") }}
               </a>
             </div>
           </template>
diff --git a/server/config/urls.py b/server/config/urls.py
index 771f4568..59959ebb 100644
--- a/server/config/urls.py
+++ b/server/config/urls.py
@@ -118,9 +118,6 @@ urlpatterns = [
 
     # course
     path(r"api/course/sessions/", get_course_sessions, name="get_course_sessions"),
-    # path(r"api/course/sessions/<signed_int:course_session_id>/users/",
-    #      get_course_session_users,
-    #      name="get_course_session_users"),
     path(r"api/course/page/<slug_or_id>/", course_page_api_view,
          name="course_page_api_view"),
     path(r"api/course/completion/mark/", mark_course_completion_view,
diff --git a/server/vbv_lernwelt/core/management/commands/cypress_reset.py b/server/vbv_lernwelt/core/management/commands/cypress_reset.py
index 7728037a..2ac68707 100644
--- a/server/vbv_lernwelt/core/management/commands/cypress_reset.py
+++ b/server/vbv_lernwelt/core/management/commands/cypress_reset.py
@@ -344,24 +344,24 @@ def command(
         attendance_course.save()
 
     if create_learning_mentor:
+        cs_bern = CourseSession.objects.get(id=TEST_COURSE_SESSION_BERN_ID)
+
         uk_mentor = LearningMentor.objects.create(
-            course=Course.objects.get(id=COURSE_TEST_ID),
             mentor=User.objects.get(id=TEST_MENTOR1_USER_ID),
+            course_session=cs_bern,
         )
         uk_mentor.participants.add(
             CourseSessionUser.objects.get(
                 user__id=TEST_STUDENT1_USER_ID,
-                course_session=CourseSession.objects.get(
-                    id=TEST_COURSE_SESSION_BERN_ID
-                ),
+                course_session=cs_bern,
             )
         )
 
         vv_course = Course.objects.get(id=COURSE_VERSICHERUNGSVERMITTLERIN_ID)
         vv_course_session = CourseSession.objects.get(course=vv_course)
         vv_mentor = LearningMentor.objects.create(
-            course=vv_course,
             mentor=User.objects.get(id=TEST_MENTOR1_USER_ID),
+            course_session=vv_course_session,
         )
 
         vv_mentor.participants.add(
@@ -371,7 +371,7 @@ def command(
         )
 
         vv_mentor.participants.add(
-            CourseSessionUser.objec.get(
+            CourseSessionUser.objects.get(
                 user__id=TEST_STUDENT2_VV_AND_VV_MENTOR_USER_ID,
                 course_session=vv_course_session,
             )
@@ -379,7 +379,7 @@ def command(
 
         vv_student_and_mentor = LearningMentor.objects.create(
             mentor=User.objects.get(id=TEST_STUDENT2_VV_AND_VV_MENTOR_USER_ID),
-            course=vv_course,
+            course_session=vv_course_session,
         )
 
         vv_student_and_mentor.participants.add(
diff --git a/server/vbv_lernwelt/course/creators/test_utils.py b/server/vbv_lernwelt/course/creators/test_utils.py
index ac99904b..fe61b8fb 100644
--- a/server/vbv_lernwelt/course/creators/test_utils.py
+++ b/server/vbv_lernwelt/course/creators/test_utils.py
@@ -100,9 +100,11 @@ def create_course_session(
 
 
 def add_learning_mentor(
-    course: Course, mentor: User, mentee: CourseSessionUser
+    course_session: CourseSession, mentor: User, mentee: CourseSessionUser
 ) -> LearningMentor:
-    learning_mentor = LearningMentor.objects.create(course=course, mentor=mentor)
+    learning_mentor = LearningMentor.objects.create(
+        course_session=course_session, mentor=mentor
+    )
     learning_mentor.participants.add(mentee)
     return learning_mentor
 
diff --git a/server/vbv_lernwelt/course/tests/test_course_session_api.py b/server/vbv_lernwelt/course/tests/test_course_session_api.py
index 1a4aaf13..97580c48 100644
--- a/server/vbv_lernwelt/course/tests/test_course_session_api.py
+++ b/server/vbv_lernwelt/course/tests/test_course_session_api.py
@@ -35,7 +35,7 @@ class CourseCompletionApiTestCase(APITestCase):
         self.assertEqual(len(response.json()), 0)
 
     def test_api_courseSession_withCourseSessionUser(self):
-        csu = CourseSessionUser.objects.create(
+        CourseSessionUser.objects.create(
             course_session=self.course_session,
             user=self.user,
         )
diff --git a/server/vbv_lernwelt/course/views.py b/server/vbv_lernwelt/course/views.py
index 80b7f238..6d1a9791 100644
--- a/server/vbv_lernwelt/course/views.py
+++ b/server/vbv_lernwelt/course/views.py
@@ -155,8 +155,8 @@ def get_course_sessions(request):
 
         # enrich with mentor course sessions
         mentor_course_sessions = CourseSession.objects.filter(
-            course__in=LearningMentor.objects.filter(mentor=request.user).values_list(
-                "course", flat=True
+            id__in=LearningMentor.objects.filter(mentor=request.user).values_list(
+                "course_session", flat=True
             )
         ).prefetch_related("course")
 
diff --git a/server/vbv_lernwelt/dashboard/graphql/queries.py b/server/vbv_lernwelt/dashboard/graphql/queries.py
index 69ced737..38c3c71f 100644
--- a/server/vbv_lernwelt/dashboard/graphql/queries.py
+++ b/server/vbv_lernwelt/dashboard/graphql/queries.py
@@ -192,14 +192,14 @@ def get_learning_mentor_dashboards(
     user: User, exclude_course_ids: Set[int]
 ) -> Tuple[List[Dict[str, str]], Set[int]]:
     learning_mentor = LearningMentor.objects.filter(mentor=user).exclude(
-        course_id__in=exclude_course_ids
+        course_session__course__id__in=exclude_course_ids
     )
 
     dashboards = []
     course_ids = set()
 
     for mentor in learning_mentor:
-        course = mentor.course
+        course = mentor.course_session.course
         course_ids.add(course.id)
         dashboards.append(
             {
diff --git a/server/vbv_lernwelt/dashboard/tests/graphql/test_dashboard.py b/server/vbv_lernwelt/dashboard/tests/graphql/test_dashboard.py
index 08ae6d7d..6373eea3 100644
--- a/server/vbv_lernwelt/dashboard/tests/graphql/test_dashboard.py
+++ b/server/vbv_lernwelt/dashboard/tests/graphql/test_dashboard.py
@@ -268,7 +268,7 @@ class DashboardTestCase(GraphQLTestCase):
             role=CourseSessionUser.Role.MEMBER,
         )
 
-        add_learning_mentor(course=course_1, mentor=mentor, mentee=csu)
+        add_learning_mentor(course_session=cs_1, mentor=mentor, mentee=csu)
 
         self.client.force_login(mentor)
 
@@ -314,7 +314,7 @@ class DashboardTestCase(GraphQLTestCase):
             role=CourseSessionUser.Role.MEMBER,
         )
 
-        add_learning_mentor(course=course, mentor=mentor_and_member, mentee=mentee)
+        add_learning_mentor(course_session=cs, mentor=mentor_and_member, mentee=mentee)
 
         # WHEN
         self.client.force_login(mentor_and_member)
diff --git a/server/vbv_lernwelt/iam/permissions.py b/server/vbv_lernwelt/iam/permissions.py
index 276bf92a..b2210c7c 100644
--- a/server/vbv_lernwelt/iam/permissions.py
+++ b/server/vbv_lernwelt/iam/permissions.py
@@ -22,7 +22,9 @@ def has_course_access(user, course_id):
     ).exists():
         return True
 
-    if LearningMentor.objects.filter(course_id=course_id, mentor=user).exists():
+    if LearningMentor.objects.filter(
+        course_session__course_id=course_id, mentor=user
+    ).exists():
         return True
 
     return CourseSessionUser.objects.filter(
@@ -71,7 +73,7 @@ def is_learning_mentor(mentor: User, course_session_id: int):
         return False
 
     return LearningMentor.objects.filter(
-        mentor=mentor, course_id=course_session.course_id
+        mentor=mentor, course_session=course_session
     ).exists()
 
 
@@ -86,7 +88,7 @@ def is_learning_mentor_for_user(
         return False
 
     return LearningMentor.objects.filter(
-        course_id=csu.course_session.course_id, mentor=mentor, participants=csu
+        course_session_id=course_session_id, mentor=mentor, participants=csu
     ).exists()
 
 
@@ -211,7 +213,9 @@ def has_role_in_course(user: User, course: Course) -> bool:
     ).exists():
         return True
 
-    if LearningMentor.objects.filter(course=course, mentor=user).exists():
+    if LearningMentor.objects.filter(
+        course_session__course=course, mentor=user
+    ).exists():
         return True
 
     if CourseSessionGroup.objects.filter(course=course, supervisor=user).exists():
diff --git a/server/vbv_lernwelt/iam/tests/test_actions.py b/server/vbv_lernwelt/iam/tests/test_actions.py
index ca365799..01b586c3 100644
--- a/server/vbv_lernwelt/iam/tests/test_actions.py
+++ b/server/vbv_lernwelt/iam/tests/test_actions.py
@@ -21,10 +21,7 @@ class ActionTestCase(TestCase):
     def test_course_session_permissions(self):
         # GIVEN
         lm = create_user("mentor")
-        LearningMentor.objects.create(
-            mentor=lm,
-            course=self.course,
-        )
+        LearningMentor.objects.create(mentor=lm, course_session=self.course_session)
 
         participant = create_user("participant")
         add_course_session_user(
diff --git a/server/vbv_lernwelt/iam/tests/test_roles.py b/server/vbv_lernwelt/iam/tests/test_roles.py
index 2b14671c..92ae9b20 100644
--- a/server/vbv_lernwelt/iam/tests/test_roles.py
+++ b/server/vbv_lernwelt/iam/tests/test_roles.py
@@ -50,7 +50,7 @@ class RoleTestCase(TestCase):
         # GIVEN
         LearningMentor.objects.create(
             mentor=self.user,
-            course=self.course,
+            course_session=self.course_session,
         )
 
         # WHEN
@@ -75,7 +75,7 @@ class RoleTestCase(TestCase):
 
         learning_mentor = LearningMentor.objects.create(
             mentor=mentor,
-            course=course,
+            course_session=course_session,
         )
 
         learning_mentor.participants.add(member_csu)
diff --git a/server/vbv_lernwelt/learning_mentor/admin.py b/server/vbv_lernwelt/learning_mentor/admin.py
index c23b8514..80387032 100644
--- a/server/vbv_lernwelt/learning_mentor/admin.py
+++ b/server/vbv_lernwelt/learning_mentor/admin.py
@@ -10,7 +10,7 @@ class LearningMentorAdmin(admin.ModelAdmin):
 
     participant_count.short_description = "Participants"
 
-    list_display = ["mentor", "course", "participant_count"]
+    list_display = ["mentor", "course_session", "participant_count"]
 
     search_fields = ["mentor__email"]
 
diff --git a/server/vbv_lernwelt/learning_mentor/migrations/0006_auto_20240319_1058.py b/server/vbv_lernwelt/learning_mentor/migrations/0006_auto_20240319_1058.py
new file mode 100644
index 00000000..a7d817b9
--- /dev/null
+++ b/server/vbv_lernwelt/learning_mentor/migrations/0006_auto_20240319_1058.py
@@ -0,0 +1,57 @@
+# Generated by Django 3.2.20 on 2024-03-19 09:58
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+def reverse_migrate_course_session_to_course(apps, schema_editor):
+    LearningMentor = apps.get_model("learning_mentor", "LearningMentor")
+    for lm in LearningMentor.objects.all():
+        lm.course = lm.course_session.course
+        lm.save()
+
+
+def migrate_course_to_course_session(apps, schema_editor):
+    LearningMentor = apps.get_model("learning_mentor", "LearningMentor")
+    CourseSession = apps.get_model("course", "CourseSession")
+
+    for lm in LearningMentor.objects.all():
+        # first is fine for VV there is only one course session per course
+        course_session = CourseSession.objects.filter(course=lm.course).first()
+        lm.course_session = course_session
+        lm.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("course", "0007_auto_20240226_1553"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ("learning_mentor", "0005_alter_learningmentor_mentor"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="learningmentor",
+            name="course_session",
+            field=models.ForeignKey(
+                # this is a dummy value, it will be replaced by the migration
+                default=-1,
+                on_delete=django.db.models.deletion.CASCADE,
+                to="course.coursesession",
+            ),
+            preserve_default=False,
+        ),
+        migrations.AlterUniqueTogether(
+            name="learningmentor",
+            unique_together={("mentor", "course_session")},
+        ),
+        migrations.RunPython(
+            code=migrate_course_to_course_session,
+            reverse_code=reverse_migrate_course_session_to_course,
+        ),
+        migrations.RemoveField(
+            model_name="learningmentor",
+            name="course",
+        ),
+    ]
diff --git a/server/vbv_lernwelt/learning_mentor/models.py b/server/vbv_lernwelt/learning_mentor/models.py
index 4db8e770..ff3c3768 100644
--- a/server/vbv_lernwelt/learning_mentor/models.py
+++ b/server/vbv_lernwelt/learning_mentor/models.py
@@ -9,7 +9,7 @@ from vbv_lernwelt.course.models import CourseSessionUser
 
 class LearningMentor(models.Model):
     mentor = models.ForeignKey(User, on_delete=models.CASCADE)
-    course = models.ForeignKey("course.Course", on_delete=models.CASCADE)
+    course_session = models.ForeignKey("course.CourseSession", on_delete=models.CASCADE)
 
     participants = models.ManyToManyField(
         CourseSessionUser,
@@ -18,7 +18,7 @@ class LearningMentor(models.Model):
     )
 
     class Meta:
-        unique_together = [["mentor", "course"]]
+        unique_together = [["mentor", "course_session"]]
         verbose_name = "Lernbegleiter"
         verbose_name_plural = "Lernbegleiter"
 
diff --git a/server/vbv_lernwelt/learning_mentor/signals.py b/server/vbv_lernwelt/learning_mentor/signals.py
index dd282f99..32cb5c72 100644
--- a/server/vbv_lernwelt/learning_mentor/signals.py
+++ b/server/vbv_lernwelt/learning_mentor/signals.py
@@ -10,7 +10,9 @@ def validate_student(sender, instance, action, reverse, model, pk_set, **kwargs)
     if action == "pre_add":
         participants = model.objects.filter(pk__in=pk_set)
         for participant in participants:
-            if participant.course_session.course != instance.course:
+            if participant.course_session != instance.course_session:
                 raise ValidationError(
                     "Participant (CourseSessionUser) does not match the course for this mentor."
                 )
+            if participant.user == instance.mentor:
+                raise ValidationError("You cannot mentor yourself.")
diff --git a/server/vbv_lernwelt/learning_mentor/tests/test_invitation.py b/server/vbv_lernwelt/learning_mentor/tests/test_invitation.py
index 67fdc4eb..115a8f18 100644
--- a/server/vbv_lernwelt/learning_mentor/tests/test_invitation.py
+++ b/server/vbv_lernwelt/learning_mentor/tests/test_invitation.py
@@ -35,6 +35,34 @@ class LearningMentorInvitationTest(APITestCase):
         # THEN
         self.assertEqual(response.status_code, status.HTTP_403_FORBIDDEN)
 
+    @patch("vbv_lernwelt.learning_mentor.views.send_email")
+    def test_create_denies_self_invitation(self, mock_send_mail) -> None:
+        # GIVEN
+        self.client.force_login(self.participant)
+
+        add_course_session_user(
+            self.course_session,
+            self.participant,
+            role=CourseSessionUser.Role.MEMBER,
+        )
+
+        invite_url = reverse(
+            "create_invitation", kwargs={"course_session_id": self.course_session.id}
+        )
+
+        # WHEN
+        email = self.participant.email
+        response = self.client.post(invite_url, data={"email": email})
+
+        # THEN
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(
+            response.data,
+            {
+                "message": "You cannot invite yourself",
+            },
+        )
+
     @patch("vbv_lernwelt.learning_mentor.views.send_email")
     def test_create_invitation(self, mock_send_mail) -> None:
         # GIVEN
@@ -164,49 +192,11 @@ class LearningMentorInvitationTest(APITestCase):
             },
         )
 
-    def test_accept_invitation_role_collision(self) -> None:
-        # GIVEN
-        participant_cs_user = add_course_session_user(
-            self.course_session,
-            self.participant,
-            role=CourseSessionUser.Role.MEMBER,
-        )
-
-        invitee = create_user("invitee")
-        invitation = MentorInvitation.objects.create(
-            participant=participant_cs_user, email=invitee.email
-        )
-        # Make invitee a trainer
-        add_course_session_user(
-            self.course_session,
-            invitee,
-            role=CourseSessionUser.Role.EXPERT,
-        )
-
-        self.client.force_login(invitee)
-
-        accept_url = reverse(
-            "accept_invitation", kwargs={"course_session_id": self.course_session.id}
-        )
-
-        # WHEN
-        response = self.client.post(accept_url, data={"invitation_id": invitation.id})
-
-        # THEN
-        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
-        self.assertEqual(
-            response.data,
-            {
-                "message": "User already has a role in this course",
-                "code": "existingRole",
-            },
-        )
-
     def test_accept_invitation(self) -> None:
         # GIVEN
         participant_cs_user = add_course_session_user(
-            self.course_session,
-            self.participant,
+            course_session=self.course_session,
+            user=self.participant,
             role=CourseSessionUser.Role.MEMBER,
         )
 
@@ -229,7 +219,9 @@ class LearningMentorInvitationTest(APITestCase):
         self.assertFalse(MentorInvitation.objects.filter(id=invitation.id).exists())
         self.assertTrue(
             LearningMentor.objects.filter(
-                mentor=invitee, course=self.course, participants=participant_cs_user
+                mentor=invitee,
+                course_session=self.course_session,
+                participants=participant_cs_user,
             ).exists()
         )
 
diff --git a/server/vbv_lernwelt/learning_mentor/tests/test_mentor.py b/server/vbv_lernwelt/learning_mentor/tests/test_mentor.py
index 617c8843..996d4dc7 100644
--- a/server/vbv_lernwelt/learning_mentor/tests/test_mentor.py
+++ b/server/vbv_lernwelt/learning_mentor/tests/test_mentor.py
@@ -77,7 +77,7 @@ class LearningMentorAPITest(APITestCase):
         # GIVEN
         self.client.force_login(self.mentor)
         LearningMentor.objects.create(
-            mentor=self.mentor, course=self.course_session.course
+            mentor=self.mentor, course_session=self.course_session
         )
 
         # WHEN
@@ -93,8 +93,7 @@ class LearningMentorAPITest(APITestCase):
         participants = [self.participant_1, self.participant_2, self.participant_3]
         self.client.force_login(self.mentor)
         mentor = LearningMentor.objects.create(
-            mentor=self.mentor,
-            course=self.course_session.course,
+            mentor=self.mentor, course_session=self.course_session
         )
         mentor.participants.set(participants)
 
@@ -120,8 +119,7 @@ class LearningMentorAPITest(APITestCase):
         self.client.force_login(self.mentor)
 
         mentor = LearningMentor.objects.create(
-            mentor=self.mentor,
-            course=self.course_session.course,
+            mentor=self.mentor, course_session=self.course_session
         )
 
         mentor.participants.set(participants)
@@ -204,7 +202,7 @@ class LearningMentorAPITest(APITestCase):
 
         mentor = LearningMentor.objects.create(
             mentor=self.mentor,
-            course=self.course_session.course,
+            course_session=self.course_session,
         )
 
         participants = [self.participant_1, self.participant_2, self.participant_3]
@@ -265,8 +263,7 @@ class LearningMentorAPITest(APITestCase):
         )
 
         learning_mentor = LearningMentor.objects.create(
-            mentor=self.mentor,
-            course=self.course_session.course,
+            mentor=self.mentor, course_session=self.course_session
         )
 
         learning_mentor.participants.add(participant_cs_user)
@@ -300,8 +297,7 @@ class LearningMentorAPITest(APITestCase):
         )
 
         learning_mentor = LearningMentor.objects.create(
-            mentor=self.mentor,
-            course=self.course_session.course,
+            mentor=self.mentor, course_session=self.course_session
         )
 
         learning_mentor.participants.add(participant_cs_user)
@@ -326,11 +322,19 @@ class LearningMentorAPITest(APITestCase):
     def test_mentor_multiple_courses(self) -> None:
         # GIVEN
         course_a, _ = create_course("Course A")
+        course_session_a = create_course_session(course=course_a, title="Test A")
+
         course_b, _ = create_course("Course B")
+        course_session_b = create_course_session(course=course_b, title="Test B")
 
         # WHEN
-        LearningMentor.objects.create(mentor=self.mentor, course=course_a)
-        LearningMentor.objects.create(mentor=self.mentor, course=course_b)
+        LearningMentor.objects.create(
+            mentor=self.mentor, course_session=course_session_a
+        )
+
+        LearningMentor.objects.create(
+            mentor=self.mentor, course_session=course_session_b
+        )
 
         # THEN
         self.assertEqual(LearningMentor.objects.count(), 2)
diff --git a/server/vbv_lernwelt/learning_mentor/views.py b/server/vbv_lernwelt/learning_mentor/views.py
index e56c33fc..d3b2c395 100644
--- a/server/vbv_lernwelt/learning_mentor/views.py
+++ b/server/vbv_lernwelt/learning_mentor/views.py
@@ -8,7 +8,7 @@ from rest_framework.response import Response
 
 from vbv_lernwelt.core.serializers import UserSerializer
 from vbv_lernwelt.course.models import CourseSession, CourseSessionUser
-from vbv_lernwelt.iam.permissions import has_role_in_course, is_course_session_member
+from vbv_lernwelt.iam.permissions import is_course_session_member
 from vbv_lernwelt.learning_mentor.content.praxis_assignment import (
     get_praxis_assignments,
 )
@@ -31,7 +31,7 @@ def mentor_summary(request, course_session_id: int):
     course_session = CourseSession.objects.get(id=course_session_id)
 
     mentor = get_object_or_404(
-        LearningMentor, mentor=request.user, course=course_session.course
+        LearningMentor, mentor=request.user, course_session=course_session
     )
 
     participants = mentor.participants.filter(course_session=course_session)
@@ -129,8 +129,13 @@ def create_invitation(request, course_session_id: int):
     if not serializer.is_valid():
         return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
-    invitation = serializer.save()
+    if serializer.validated_data.get("email") == user.email:
+        return Response(
+            data={"message": "You cannot invite yourself"},
+            status=status.HTTP_400_BAD_REQUEST,
+        )
 
+    invitation = serializer.save()
     target_url = f"/lernbegleitung/{course_session_id}/invitation/{invitation.id}"
 
     send_email(
@@ -158,7 +163,7 @@ def list_user_mentors(request, course_session_id: int):
     )
 
     mentors = LearningMentor.objects.filter(
-        course=course_session.course, participants=course_session_user
+        course_session=course_session, participants=course_session_user
     )
 
     return Response(MentorSerializer(mentors, many=True).data)
@@ -193,25 +198,9 @@ def accept_invitation(request, course_session_id: int):
             status=status.HTTP_400_BAD_REQUEST,
         )
 
-    if LearningMentor.objects.filter(
-        mentor=request.user, course=course_session.course
-    ).exists():
-        mentor = LearningMentor.objects.get(
-            mentor=request.user, course=course_session.course
-        )
-    else:
-        if has_role_in_course(request.user, course_session.course):
-            return Response(
-                data={
-                    "message": "User already has a role in this course",
-                    "code": "existingRole",
-                },
-                status=status.HTTP_400_BAD_REQUEST,
-            )
-
-        mentor = LearningMentor.objects.create(
-            mentor=request.user, course=course_session.course
-        )
+    mentor, _ = LearningMentor.objects.get_or_create(
+        mentor=request.user, course_session=course_session
+    )
 
     mentor.participants.add(invitation.participant)
     invitation.delete()
diff --git a/server/vbv_lernwelt/self_evaluation_feedback/tests/test_api.py b/server/vbv_lernwelt/self_evaluation_feedback/tests/test_api.py
index 08a05495..adb22c0b 100644
--- a/server/vbv_lernwelt/self_evaluation_feedback/tests/test_api.py
+++ b/server/vbv_lernwelt/self_evaluation_feedback/tests/test_api.py
@@ -53,7 +53,7 @@ class SelfEvaluationFeedbackAPI(APITestCase):
 
         learning_mentor = LearningMentor.objects.create(
             mentor=self.mentor,
-            course=self.course_session.course,
+            course_session=self.course_session,
         )
 
         learning_mentor.participants.add(member_csu)
diff --git a/server/vbv_lernwelt/self_evaluation_feedback/views.py b/server/vbv_lernwelt/self_evaluation_feedback/views.py
index 31e772f8..f725273c 100644
--- a/server/vbv_lernwelt/self_evaluation_feedback/views.py
+++ b/server/vbv_lernwelt/self_evaluation_feedback/views.py
@@ -39,7 +39,7 @@ def start_self_evaluation_feedback(request, learning_unit_id):
     feedback_provider_user = get_object_or_404(User, id=feedback_provider_user_id)
 
     if not LearningMentor.objects.filter(
-        course=learning_unit.get_course(),
+        course_session__course=learning_unit.get_course(),
         mentor=feedback_provider_user,
         participants__user=request.user,
     ).exists():