diff --git a/frontend/src/routes/admin/groups/[id]/page.server.spec.ts b/frontend/src/routes/admin/groups/[id]/page.server.spec.ts
index 1407e102..53b3e419 100644
--- a/frontend/src/routes/admin/groups/[id]/page.server.spec.ts
+++ b/frontend/src/routes/admin/groups/[id]/page.server.spec.ts
@@ -7,7 +7,8 @@ const mockApi = {
 };
 
 vi.mock('$lib/shared/api.server', () => ({
-	createApiClient: () => mockApi
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
 }));
 
 beforeEach(() => vi.clearAllMocks());
diff --git a/frontend/src/routes/admin/groups/layout.server.spec.ts b/frontend/src/routes/admin/groups/layout.server.spec.ts
index 08cff99c..c23bddc1 100644
--- a/frontend/src/routes/admin/groups/layout.server.spec.ts
+++ b/frontend/src/routes/admin/groups/layout.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+layout.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { createApiClient } from '$lib/shared/api.server';
 
diff --git a/frontend/src/routes/admin/layout.server.spec.ts b/frontend/src/routes/admin/layout.server.spec.ts
index 0fb89809..034f077f 100644
--- a/frontend/src/routes/admin/layout.server.spec.ts
+++ b/frontend/src/routes/admin/layout.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+layout.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { createApiClient } from '$lib/shared/api.server';
 
diff --git a/frontend/src/routes/admin/ocr/[personId]/page.server.spec.ts b/frontend/src/routes/admin/ocr/[personId]/page.server.spec.ts
index 4d2f6ef7..fe300b5e 100644
--- a/frontend/src/routes/admin/ocr/[personId]/page.server.spec.ts
+++ b/frontend/src/routes/admin/ocr/[personId]/page.server.spec.ts
@@ -3,7 +3,10 @@ import { load } from './+page.server';
 
 const mockApi = { GET: vi.fn() };
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: () => mockApi }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 beforeEach(() => vi.clearAllMocks());
 
diff --git a/frontend/src/routes/admin/ocr/global/page.server.spec.ts b/frontend/src/routes/admin/ocr/global/page.server.spec.ts
index b96438de..eab91036 100644
--- a/frontend/src/routes/admin/ocr/global/page.server.spec.ts
+++ b/frontend/src/routes/admin/ocr/global/page.server.spec.ts
@@ -3,7 +3,10 @@ import { load } from './+page.server';
 
 const mockApi = { GET: vi.fn() };
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: () => mockApi }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 beforeEach(() => vi.clearAllMocks());
 
diff --git a/frontend/src/routes/admin/ocr/page.server.spec.ts b/frontend/src/routes/admin/ocr/page.server.spec.ts
index a7c4f019..a2df41d0 100644
--- a/frontend/src/routes/admin/ocr/page.server.spec.ts
+++ b/frontend/src/routes/admin/ocr/page.server.spec.ts
@@ -3,7 +3,10 @@ import { load } from './+page.server';
 
 const mockApi = { GET: vi.fn() };
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: () => mockApi }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 beforeEach(() => vi.clearAllMocks());
 
diff --git a/frontend/src/routes/admin/tags/[id]/page.server.spec.ts b/frontend/src/routes/admin/tags/[id]/page.server.spec.ts
index c8b724c0..ce7b5e7d 100644
--- a/frontend/src/routes/admin/tags/[id]/page.server.spec.ts
+++ b/frontend/src/routes/admin/tags/[id]/page.server.spec.ts
@@ -8,7 +8,8 @@ const mockApi = {
 };
 
 vi.mock('$lib/shared/api.server', () => ({
-	createApiClient: () => mockApi
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
 }));
 
 beforeEach(() => vi.clearAllMocks());
diff --git a/frontend/src/routes/admin/tags/layout.server.spec.ts b/frontend/src/routes/admin/tags/layout.server.spec.ts
index d50440f5..9dd91504 100644
--- a/frontend/src/routes/admin/tags/layout.server.spec.ts
+++ b/frontend/src/routes/admin/tags/layout.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+layout.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { createApiClient } from '$lib/shared/api.server';
 
diff --git a/frontend/src/routes/admin/users/[id]/page.server.spec.ts b/frontend/src/routes/admin/users/[id]/page.server.spec.ts
index da2f3921..1199a880 100644
--- a/frontend/src/routes/admin/users/[id]/page.server.spec.ts
+++ b/frontend/src/routes/admin/users/[id]/page.server.spec.ts
@@ -4,7 +4,10 @@ vi.mock('$env/dynamic/private', () => ({
 	env: { API_INTERNAL_URL: 'http://localhost:8080' }
 }));
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { load, actions } from './+page.server';
 import { createApiClient } from '$lib/shared/api.server';
diff --git a/frontend/src/routes/admin/users/layout.server.spec.ts b/frontend/src/routes/admin/users/layout.server.spec.ts
index bd4ab7ff..6bc0144a 100644
--- a/frontend/src/routes/admin/users/layout.server.spec.ts
+++ b/frontend/src/routes/admin/users/layout.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+layout.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { createApiClient } from '$lib/shared/api.server';
 
diff --git a/frontend/src/routes/aktivitaeten/page.server.spec.ts b/frontend/src/routes/aktivitaeten/page.server.spec.ts
index 31a1619f..f2521954 100644
--- a/frontend/src/routes/aktivitaeten/page.server.spec.ts
+++ b/frontend/src/routes/aktivitaeten/page.server.spec.ts
@@ -6,7 +6,8 @@ const mockApi = {
 };
 
 vi.mock('$lib/shared/api.server', () => ({
-	createApiClient: () => mockApi
+	createApiClient: () => mockApi,
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
 }));
 
 function buildUrl(search = ''): URL {
diff --git a/frontend/src/routes/briefwechsel/page.server.spec.ts b/frontend/src/routes/briefwechsel/page.server.spec.ts
index 1c8232ef..5329e896 100644
--- a/frontend/src/routes/briefwechsel/page.server.spec.ts
+++ b/frontend/src/routes/briefwechsel/page.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+page.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 vi.mock('$lib/shared/errors', () => ({
 	getErrorMessage: (code: string) => code ?? 'Unknown error'
 }));
diff --git a/frontend/src/routes/documents/[id]/page.server.spec.ts b/frontend/src/routes/documents/[id]/page.server.spec.ts
index f2735a9e..777a77db 100644
--- a/frontend/src/routes/documents/[id]/page.server.spec.ts
+++ b/frontend/src/routes/documents/[id]/page.server.spec.ts
@@ -1,6 +1,9 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 vi.mock('$env/dynamic/private', () => ({ env: { API_INTERNAL_URL: 'http://test-backend:8080' } }));
 
 import { load } from './+page.server';
diff --git a/frontend/src/routes/documents/page.server.spec.ts b/frontend/src/routes/documents/page.server.spec.ts
index ac71972f..2ed33a86 100644
--- a/frontend/src/routes/documents/page.server.spec.ts
+++ b/frontend/src/routes/documents/page.server.spec.ts
@@ -1,6 +1,9 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { load } from './+page.server';
 import { createApiClient } from '$lib/shared/api.server';
diff --git a/frontend/src/routes/page.server.spec.ts b/frontend/src/routes/page.server.spec.ts
index 9ffae2b9..b87ce9a8 100644
--- a/frontend/src/routes/page.server.spec.ts
+++ b/frontend/src/routes/page.server.spec.ts
@@ -1,6 +1,9 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { load } from './+page.server';
 import { createApiClient } from '$lib/shared/api.server';
diff --git a/frontend/src/routes/persons/[id]/page.server.spec.ts b/frontend/src/routes/persons/[id]/page.server.spec.ts
index c2fc6dea..a855716d 100644
--- a/frontend/src/routes/persons/[id]/page.server.spec.ts
+++ b/frontend/src/routes/persons/[id]/page.server.spec.ts
@@ -1,7 +1,10 @@
 import { describe, expect, it, vi, beforeEach } from 'vitest';
 import { load } from './+page.server';
 
-vi.mock('$lib/shared/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$lib/shared/api.server', () => ({
+	createApiClient: vi.fn(),
+	extractErrorCode: (e: unknown) => (e as { code?: string } | undefined)?.code
+}));
 
 import { createApiClient } from '$lib/shared/api.server';