diff --git a/client/src/pages/cockpit/CockpitUserCirclePage.vue b/client/src/pages/cockpit/CockpitUserCirclePage.vue
index 4014e9cc..4d3b922f 100644
--- a/client/src/pages/cockpit/CockpitUserCirclePage.vue
+++ b/client/src/pages/cockpit/CockpitUserCirclePage.vue
@@ -19,9 +19,7 @@ onMounted(async () => {
 });
 
 const user = computed(() => {
-  return cockpitStore.courseSessionUsers?.find(
-    (csu) => csu.user_id === Number(props.userId)
-  );
+  return cockpitStore.courseSessionUsers?.find((csu) => csu.user_id === props.userId);
 });
 </script>
 
diff --git a/client/src/pages/cockpit/CockpitUserProfilePage.vue b/client/src/pages/cockpit/CockpitUserProfilePage.vue
index af001329..2634129e 100644
--- a/client/src/pages/cockpit/CockpitUserProfilePage.vue
+++ b/client/src/pages/cockpit/CockpitUserProfilePage.vue
@@ -28,9 +28,7 @@ const learningPath = computed(() => {
 });
 
 const user = computed(() => {
-  return cockpitStore.courseSessionUsers?.find(
-    (csu) => csu.user_id === Number(props.userId)
-  );
+  return cockpitStore.courseSessionUsers?.find((csu) => csu.user_id === props.userId);
 });
 
 function setActiveClasses(isActive: boolean) {
diff --git a/client/src/pages/cockpit/assignmentEvaluationPage/AssignmentEvaluationPage.vue b/client/src/pages/cockpit/assignmentEvaluationPage/AssignmentEvaluationPage.vue
index fad881a7..d00ea917 100644
--- a/client/src/pages/cockpit/assignmentEvaluationPage/AssignmentEvaluationPage.vue
+++ b/client/src/pages/cockpit/assignmentEvaluationPage/AssignmentEvaluationPage.vue
@@ -49,7 +49,7 @@ onMounted(async () => {
   log.debug("AssignmentView mounted", props.assignmentId, props.userId);
 
   state.assignmentUser = courseSession.value.users.find(
-    (user) => user.user_id === Number(props.userId)
+    (user) => user.user_id === props.userId
   );
 });
 
diff --git a/client/src/pages/cockpit/assignmentEvaluationPage/EvaluationSummary.vue b/client/src/pages/cockpit/assignmentEvaluationPage/EvaluationSummary.vue
index a8a00790..2826bb50 100644
--- a/client/src/pages/cockpit/assignmentEvaluationPage/EvaluationSummary.vue
+++ b/client/src/pages/cockpit/assignmentEvaluationPage/EvaluationSummary.vue
@@ -88,7 +88,7 @@ const grade = computed(() => {
 const evaluationUser = computed(() => {
   if (props.assignmentCompletion.evaluation_user) {
     return (courseSession.value.users ?? []).find(
-      (user) => user.user_id === Number(props.assignmentCompletion.evaluation_user)
+      (user) => user.user_id === props.assignmentCompletion.evaluation_user
     ) as CourseSessionUser;
   }
 
diff --git a/client/src/pages/cockpit/assignmentsPage/AssignmentDetails.vue b/client/src/pages/cockpit/assignmentsPage/AssignmentDetails.vue
index 79fd16fc..90e0c48b 100644
--- a/client/src/pages/cockpit/assignmentsPage/AssignmentDetails.vue
+++ b/client/src/pages/cockpit/assignmentsPage/AssignmentDetails.vue
@@ -32,7 +32,7 @@ const state = reactive({
   statusByUser: [] as {
     userStatus: AssignmentCompletionStatus;
     progressStatus: StatusCountKey;
-    userId: number;
+    userId: string;
     grade: number | null;
   }[],
   progressStatusCount: {} as StatusCount,
@@ -45,7 +45,7 @@ onMounted(async () => {
   );
 });
 
-function submissionStatusForUser(userId: number) {
+function submissionStatusForUser(userId: string) {
   return state.statusByUser.find((s) => s.userId === userId);
 }
 
diff --git a/client/src/pages/cockpit/assignmentsPage/AssignmentSubmissionProgress.vue b/client/src/pages/cockpit/assignmentsPage/AssignmentSubmissionProgress.vue
index 13f20597..1cda4f89 100644
--- a/client/src/pages/cockpit/assignmentsPage/AssignmentSubmissionProgress.vue
+++ b/client/src/pages/cockpit/assignmentsPage/AssignmentSubmissionProgress.vue
@@ -26,7 +26,7 @@ const state = reactive({
   statusByUser: [] as {
     userStatus: AssignmentCompletionStatus;
     progressStatus: StatusCountKey;
-    userId: number;
+    userId: string;
   }[],
   progressStatusCount: {} as StatusCount,
 });
diff --git a/client/src/pages/cockpit/cockpitPage/CockpitPage.vue b/client/src/pages/cockpit/cockpitPage/CockpitPage.vue
index d1630f85..1dc938ef 100644
--- a/client/src/pages/cockpit/cockpitPage/CockpitPage.vue
+++ b/client/src/pages/cockpit/cockpitPage/CockpitPage.vue
@@ -26,7 +26,7 @@ const competenceStore = useCompetenceStore();
 const learningPathStore = useLearningPathStore();
 const courseSession = useCurrentCourseSession();
 
-function userCountStatusForCircle(userId: number, translationKey: string) {
+function userCountStatusForCircle(userId: string, translationKey: string) {
   const criteria = competenceStore.flatPerformanceCriteria(
     userId,
     cockpitStore.selectedCircles
diff --git a/client/src/pages/learningPath/learningContentPage/assignment/AssignmentView.vue b/client/src/pages/learningPath/learningContentPage/assignment/AssignmentView.vue
index 4456097d..aab338fa 100644
--- a/client/src/pages/learningPath/learningContentPage/assignment/AssignmentView.vue
+++ b/client/src/pages/learningPath/learningContentPage/assignment/AssignmentView.vue
@@ -188,7 +188,7 @@ const subTitle = computed(() => {
 
 const assignmentUser = computed(() => {
   return courseSession.value.users.find(
-    (user) => user.user_id === Number(userStore.id)
+    (user) => user.user_id === userStore.id
   ) as CourseSessionUser;
 });
 
diff --git a/client/src/services/files.ts b/client/src/services/files.ts
index f1fc522b..726d1bb2 100644
--- a/client/src/services/files.ts
+++ b/client/src/services/files.ts
@@ -98,6 +98,6 @@ export async function uploadCircleDocument(
   return Promise.resolve(newDocument);
 }
 
-export async function deleteCircleDocument(documentId: number) {
+export async function deleteCircleDocument(documentId: string) {
   return itDelete(`/api/core/document/${documentId}/`);
 }
diff --git a/client/src/services/learningPath.ts b/client/src/services/learningPath.ts
index 78e7feed..bd4c6bbb 100644
--- a/client/src/services/learningPath.ts
+++ b/client/src/services/learningPath.ts
@@ -41,7 +41,7 @@ export class LearningPath implements WagtailLearningPath {
   public static fromJson(
     json: WagtailLearningPath,
     completionData: CourseCompletion[],
-    userId: number | undefined
+    userId: string | undefined
   ): LearningPath {
     return new LearningPath(
       json.id,
@@ -64,7 +64,7 @@ export class LearningPath implements WagtailLearningPath {
     public readonly frontend_url: string,
     public readonly course: Course,
     public children: LearningPathChild[],
-    public userId: number | undefined,
+    public userId: string | undefined,
     completionData?: CourseCompletion[]
   ) {
     // parse children
diff --git a/client/src/stores/circle.ts b/client/src/stores/circle.ts
index 69eeedd7..8a0e6c41 100644
--- a/client/src/stores/circle.ts
+++ b/client/src/stores/circle.ts
@@ -41,7 +41,7 @@ export const useCircleStore = defineStore({
     async loadCircle(
       courseSlug: string,
       circleSlug: string,
-      userId: number | undefined = undefined
+      userId: string | undefined = undefined
     ): Promise<Circle> {
       if (!userId) {
         const userStore = useUserStore();
diff --git a/client/src/stores/competence.ts b/client/src/stores/competence.ts
index 5865a9d3..cd190c95 100644
--- a/client/src/stores/competence.ts
+++ b/client/src/stores/competence.ts
@@ -14,7 +14,7 @@ import orderBy from "lodash/orderBy";
 import { defineStore } from "pinia";
 
 export type CompetenceStoreState = {
-  competenceProfilePages: Map<number, CompetenceProfilePage>;
+  competenceProfilePages: Map<string, CompetenceProfilePage>;
 
   selectedCircle: { id: string; name: string };
   availableCircles: { id: string; name: string }[];
@@ -24,7 +24,7 @@ export const useCompetenceStore = defineStore({
   id: "competence",
   state: () => {
     return {
-      competenceProfilePages: new Map<number, CompetenceProfilePage>(),
+      competenceProfilePages: new Map<string, CompetenceProfilePage>(),
       selectedCircle: { id: "all", name: "Circle: Alle" },
       availableCircles: [],
     } as CompetenceStoreState;
@@ -56,7 +56,7 @@ export const useCompetenceStore = defineStore({
         return competence.children;
       });
     },
-    competenceProfilePage(userId: number | undefined = undefined) {
+    competenceProfilePage(userId: string | undefined = undefined) {
       if (!userId) {
         const userStore = useUserStore();
         userId = userStore.id;
@@ -65,7 +65,7 @@ export const useCompetenceStore = defineStore({
       return this.competenceProfilePages.get(userId);
     },
     flatPerformanceCriteria(
-      userId: number | undefined = undefined,
+      userId: string | undefined = undefined,
       circleTranslationKeys: string[] | undefined = undefined
     ) {
       if (!userId) {
@@ -102,7 +102,7 @@ export const useCompetenceStore = defineStore({
 
       return [];
     },
-    competences(userId: number | undefined = undefined) {
+    competences(userId: string | undefined = undefined) {
       if (!userId) {
         const userStore = useUserStore();
         userId = userStore.id;
@@ -128,7 +128,7 @@ export const useCompetenceStore = defineStore({
     },
     async loadCompetenceProfilePage(
       slug: string,
-      userId: number | undefined = undefined,
+      userId: string | undefined = undefined,
       reload = false
     ) {
       if (!userId) {
@@ -161,7 +161,7 @@ export const useCompetenceStore = defineStore({
 
       return this.competenceProfilePages.get(userId);
     },
-    async parseCompletionData(userId: number) {
+    async parseCompletionData(userId: string) {
       const competenceProfilePage = this.competenceProfilePages.get(userId);
       if (competenceProfilePage) {
         const completionStore = useCompletionStore();
diff --git a/client/src/stores/completion.ts b/client/src/stores/completion.ts
index 4bc82f75..515d392a 100644
--- a/client/src/stores/completion.ts
+++ b/client/src/stores/completion.ts
@@ -13,7 +13,7 @@ export const useCompletionStore = defineStore({
   actions: {
     async loadCourseSessionCompletionData(
       courseSessionId: number,
-      userId: number,
+      userId: string,
       reload = false
     ) {
       const userCompletionData = (await itGetCached(
@@ -30,7 +30,7 @@ export const useCompletionStore = defineStore({
     },
     async markPage(
       page: BaseCourseWagtailPage,
-      userId: number | undefined = undefined,
+      userId: string | undefined = undefined,
       courseSessionId: number | undefined = undefined
     ) {
       if (!courseSessionId) {
diff --git a/client/src/stores/courseSessions.ts b/client/src/stores/courseSessions.ts
index ada625f0..0f1664b8 100644
--- a/client/src/stores/courseSessions.ts
+++ b/client/src/stores/courseSessions.ts
@@ -213,7 +213,7 @@ export const useCourseSessionsStore = defineStore("courseSessions", () => {
     });
   }
 
-  async function removeDocument(documentId: number) {
+  async function removeDocument(documentId: string) {
     await deleteCircleDocument(documentId);
 
     if (currentCourseSession.value === undefined) {
diff --git a/client/src/stores/learningPath.ts b/client/src/stores/learningPath.ts
index 97e3bf7e..84dba48a 100644
--- a/client/src/stores/learningPath.ts
+++ b/client/src/stores/learningPath.ts
@@ -43,7 +43,7 @@ export const useLearningPathStore = defineStore("learningPath", () => {
 
   async function loadCourseSessionCompletionData(
     courseSlug: string,
-    userId: number | undefined = undefined
+    userId: string | undefined = undefined
   ) {
     // FIXME: should not be here anymore with VBV-305
     const completionStore = useCompletionStore();
@@ -66,7 +66,7 @@ export const useLearningPathStore = defineStore("learningPath", () => {
 
   async function loadLearningPath(
     slug: string,
-    userId: number | undefined = undefined,
+    userId: string | undefined = undefined,
     reload = false,
     fail = true
   ) {
diff --git a/client/src/stores/user.ts b/client/src/stores/user.ts
index e39549e2..7c2eee33 100644
--- a/client/src/stores/user.ts
+++ b/client/src/stores/user.ts
@@ -19,7 +19,7 @@ if (import.meta.env.VITE_OAUTH_API_BASE_URL) {
 export type AvailableLanguages = "de" | "fr" | "it";
 
 export type UserState = {
-  id: number;
+  id: string;
   first_name: string;
   last_name: string;
   email: string;
@@ -50,7 +50,7 @@ for (const language of languagesWithoutCountryCode) {
 }
 
 const initialUserState: UserState = {
-  id: 0,
+  id: "",
   email: "",
   first_name: "",
   last_name: "",
diff --git a/client/src/types.ts b/client/src/types.ts
index e354fedf..1982b820 100644
--- a/client/src/types.ts
+++ b/client/src/types.ts
@@ -170,7 +170,7 @@ export interface Topic extends BaseCourseWagtailPage {
 export type LearningPathChild = Topic | WagtailCircle;
 
 export interface CourseCompletion {
-  readonly id: number;
+  readonly id: string;
   created_at: string;
   updated_at: string;
   readonly user: number;
@@ -181,17 +181,6 @@ export interface CourseCompletion {
   additional_json_data: unknown;
 }
 
-export interface CircleDiagramData {
-  index: number;
-  title: string;
-  icon: string;
-  startAngle: number;
-  endAngle: number;
-  arrowStartAngle: number;
-  arrowEndAngle: number;
-  done: boolean;
-}
-
 export interface Course {
   id: number;
   title: string;
@@ -394,7 +383,7 @@ export interface DropdownSelectable {
 }
 
 export interface CircleExpert {
-  user_id: number;
+  user_id: string;
   user_email: string;
   user_first_name: string;
   user_last_name: string;
@@ -404,7 +393,7 @@ export interface CircleExpert {
 }
 
 export interface CircleDocument {
-  id: number;
+  id: string;
   name: string;
   file_name: string;
   url: string;
@@ -457,7 +446,7 @@ export type Role = "MEMBER" | "EXPERT" | "TUTOR";
 
 export interface CourseSessionUser {
   session_title: string;
-  user_id: number;
+  user_id: string;
   first_name: string;
   last_name: string;
   email: string;
@@ -491,7 +480,7 @@ export type NotificationType = "USER_INTERACTION" | "PROGRESS" | "INFORMATION";
 
 export interface Notification {
   // given by AbstractNotification model
-  id: number;
+  id: string;
   timestamp: string;
   unread: boolean;
   actor: string | null;
@@ -532,16 +521,16 @@ export interface AssignmentCompletionData {
 }
 
 export interface AssignmentCompletion {
-  id: number;
+  id: string;
   created_at: string;
   updated_at: string;
   submitted_at: string;
   evaluation_submitted_at: string | null;
-  assignment_user: number;
+  assignment_user: string;
   assignment: number;
   course_session: number;
   completion_status: AssignmentCompletionStatus;
-  evaluation_user: number | null;
+  evaluation_user: string | null;
   completion_data: AssignmentCompletionData;
   evaluation_grade: number | null;
 }
@@ -554,14 +543,14 @@ export type UpsertUserAssignmentCompletion = {
 };
 
 export type EvaluationCompletionData = UpsertUserAssignmentCompletion & {
-  assignment_user_id: number;
+  assignment_user_id: string;
   evaluation_grade?: number;
   evaluation_points?: number;
 };
 
 export interface UserAssignmentCompletionStatus {
-  id: number;
-  assignment_user_id: number;
+  id: string;
+  assignment_user_id: string;
   completion_status: AssignmentCompletionStatus;
   evaluation_grade: number | null;
 }
diff --git a/server/config/urls.py b/server/config/urls.py
index b0912a61..30d1ecbb 100644
--- a/server/config/urls.py
+++ b/server/config/urls.py
@@ -10,6 +10,9 @@ from django.views import defaults as default_views
 from django.views.decorators.csrf import csrf_exempt
 from graphene_django.views import GraphQLView
 from ratelimit.exceptions import Ratelimited
+from wagtail import urls as wagtail_urls
+from wagtail.admin import urls as wagtailadmin_urls
+from wagtail.documents import urls as wagtaildocs_urls
 
 from vbv_lernwelt.assignment.views import request_assignment_completion_status
 from vbv_lernwelt.core.middleware.auth import django_view_authentication_exempt
@@ -42,9 +45,6 @@ from vbv_lernwelt.feedback.views import (
     get_feedback_for_circle,
 )
 from vbv_lernwelt.notify.views import email_notification_settings
-from wagtail import urls as wagtail_urls
-from wagtail.admin import urls as wagtailadmin_urls
-from wagtail.documents import urls as wagtaildocs_urls
 
 
 class SignedIntConverter(IntConverter):
@@ -109,7 +109,7 @@ urlpatterns = [
     path(r"api/course/completion/<signed_int:course_session_id>/",
          request_course_completion,
          name="request_course_completion"),
-    path(r"api/course/completion/<signed_int:course_session_id>/<signed_int:user_id>/",
+    path(r"api/course/completion/<signed_int:course_session_id>/<uuid:user_id>/",
          request_course_completion_for_user,
          name="request_course_completion_for_user"),