diff --git a/README.md b/README.md
index 248347927..e0ebef01b 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,10 @@ Optional: set `API_URL` to change the base URL used by internal UI API calls.
 Relative paths are served under `BASE_PATH`; absolute URLs are proxied through the local `/api` route.
 For example, `API_URL=/internal-api` or `API_URL=https://api.example.com/api`.
 
+Optional: set `TWO_FACTOR_ENCRYPTION_KEY` to a 64-character hex string to enable two-factor
+authentication. Generate one with `openssl rand -hex 32`. Two-factor authentication is unavailable
+and cannot be required until this key is set.
+
 The connection URL format:
 
 ```bash
diff --git a/docker-compose.yml b/docker-compose.yml
index 348c294ca..53f73b8de 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -7,6 +7,8 @@ services:
     environment:
       DATABASE_URL: postgresql://umami:umami@db:5432/umami
       APP_SECRET: replace-me-with-a-random-string
+      # Required for two-factor authentication, generate with: openssl rand -hex 32
+      TWO_FACTOR_ENCRYPTION_KEY: replace-me-with-a-64-character-hex-string
     depends_on:
       db:
         condition: service_healthy
diff --git a/public/intl/messages/en-US.json b/public/intl/messages/en-US.json
index 552381ef1..0ed5102da 100644
--- a/public/intl/messages/en-US.json
+++ b/public/intl/messages/en-US.json
@@ -505,6 +505,7 @@
     "two-factor-error-already-enabled": "Two-factor authentication is already enabled.",
     "two-factor-error-not-enabled": "Two-factor authentication is not enabled.",
     "two-factor-error-no-pending-setup": "No pending two-factor authentication setup found.",
+    "two-factor-error-not-configured": "Two-factor authentication is not available because the server is missing a valid TWO_FACTOR_ENCRYPTION_KEY. Contact your administrator for help.",
     "two-factor-locked-message": "Too many failed attempts. Try again at {time}.",
     "two-factor-active-description": "Your account is protected with two-factor authentication. Each login requires a code from your authenticator app."
   }
diff --git a/src/app/api/2fa/setup/initiate/route.test.ts b/src/app/api/2fa/setup/initiate/route.test.ts
index 04d605e2b..055cb8d3f 100644
--- a/src/app/api/2fa/setup/initiate/route.test.ts
+++ b/src/app/api/2fa/setup/initiate/route.test.ts
@@ -8,6 +8,7 @@ const mocks = vi.hoisted(() => ({
   upsert: vi.fn(),
   generateTotpSecret: vi.fn(),
   encryptSecret: vi.fn(),
+  isTwoFactorConfigured: vi.fn(),
   generateOtpAuthUri: vi.fn(),
   generateQrCodeDataUrl: vi.fn(),
 }));
@@ -33,6 +34,7 @@ vi.mock('@/lib/prisma', () => ({
 
 vi.mock('@/lib/two-factor/crypto', () => ({
   encryptSecret: mocks.encryptSecret,
+  isTwoFactorConfigured: mocks.isTwoFactorConfigured,
 }));
 
 vi.mock('@/lib/two-factor/totp', () => ({
@@ -48,9 +50,11 @@ beforeEach(() => {
   mocks.upsert.mockReset();
   mocks.generateTotpSecret.mockReset();
   mocks.encryptSecret.mockReset();
+  mocks.isTwoFactorConfigured.mockReset();
   mocks.generateOtpAuthUri.mockReset();
   mocks.generateQrCodeDataUrl.mockReset();
 
+  mocks.isTwoFactorConfigured.mockReturnValue(true);
   mocks.parseRequest.mockResolvedValue({
     auth: { user: { id: 'user-1' } },
     error: undefined,
@@ -82,6 +86,22 @@ test('POST creates a pending 2FA setup and returns the manual key and QR data',
   expect(response.status).toBe(200);
 });
 
+test('POST reports a configuration error when the encryption key is missing', async () => {
+  mocks.isTwoFactorConfigured.mockReturnValue(false);
+
+  const response = await POST(
+    new Request('http://localhost/api/2fa/setup/initiate', { method: 'POST' }),
+  );
+
+  expect(mocks.upsert).not.toHaveBeenCalled();
+  await expect(response.json()).resolves.toMatchObject({
+    error: {
+      code: 'two-factor-error-not-configured',
+    },
+  });
+  expect(response.status).toBe(503);
+});
+
 test('POST rejects setup when 2FA is already enabled for the user', async () => {
   mocks.findUnique.mockResolvedValue({ userId: 'user-1', isEnabled: true });
 
diff --git a/src/app/api/2fa/setup/initiate/route.ts b/src/app/api/2fa/setup/initiate/route.ts
index 01288601e..2ad68da61 100644
--- a/src/app/api/2fa/setup/initiate/route.ts
+++ b/src/app/api/2fa/setup/initiate/route.ts
@@ -1,6 +1,6 @@
 import { parseRequest } from '@/lib/request';
-import { badRequest, json, notFound } from '@/lib/response';
-import { encryptSecret } from '@/lib/two-factor/crypto';
+import { badRequest, json, notFound, serviceUnavailable } from '@/lib/response';
+import { encryptSecret, isTwoFactorConfigured } from '@/lib/two-factor/crypto';
 import {
   generateOtpAuthUri,
   generateQrCodeDataUrl,
@@ -20,6 +20,14 @@ export async function POST(request: Request) {
     return error();
   }
 
+  // Secrets cannot be stored without an encryption key
+  if (!isTwoFactorConfigured()) {
+    return serviceUnavailable({
+      code: 'two-factor-error-not-configured',
+      message: 'TWO_FACTOR_ENCRYPTION_KEY is missing or invalid',
+    });
+  }
+
   const userId = auth.user.id;
   const user = await getUser(userId);
 
diff --git a/src/app/api/2fa/status/route.test.ts b/src/app/api/2fa/status/route.test.ts
new file mode 100644
index 000000000..c1e4f090d
--- /dev/null
+++ b/src/app/api/2fa/status/route.test.ts
@@ -0,0 +1,89 @@
+import { beforeEach, expect, test, vi } from 'vitest';
+import prisma from '@/lib/prisma';
+import { parseRequest } from '@/lib/request';
+import { GET } from './route';
+
+const KEY = 'a'.repeat(64);
+
+vi.mock('@/lib/request', () => ({
+  parseRequest: vi.fn(),
+}));
+
+vi.mock('@/lib/prisma', () => ({
+  default: {
+    client: {
+      twoFactorAuth: {
+        findUnique: vi.fn(),
+      },
+      appSetting: {
+        findUnique: vi.fn(),
+      },
+      user: {
+        findUnique: vi.fn(),
+      },
+      teamUser: {
+        findMany: vi.fn(),
+      },
+      team: {
+        findMany: vi.fn(),
+      },
+    },
+  },
+}));
+
+const parseRequestMock = vi.mocked(parseRequest);
+const prismaMock = vi.mocked(prisma, true);
+
+beforeEach(() => {
+  vi.unstubAllEnvs();
+  parseRequestMock.mockReset();
+  prismaMock.client.twoFactorAuth.findUnique.mockReset();
+  prismaMock.client.appSetting.findUnique.mockReset();
+  prismaMock.client.user.findUnique.mockReset();
+  prismaMock.client.teamUser.findMany.mockReset();
+  prismaMock.client.team.findMany.mockReset();
+
+  parseRequestMock.mockResolvedValue({
+    auth: {
+      user: {
+        id: 'user-1',
+      },
+    },
+    error: undefined,
+  });
+  prismaMock.client.twoFactorAuth.findUnique.mockResolvedValue(null as any);
+  prismaMock.client.appSetting.findUnique.mockResolvedValue({
+    key: 'twoFactorRequiredGlobal',
+    value: 'true',
+  } as any);
+  prismaMock.client.user.findUnique.mockResolvedValue({ twoFactorRequired: false } as any);
+  prismaMock.client.teamUser.findMany.mockResolvedValue([] as any);
+  prismaMock.client.team.findMany.mockResolvedValue([] as any);
+});
+
+test('GET requires 2FA when it is globally enabled', async () => {
+  vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', KEY);
+
+  const response = await GET(new Request('http://localhost/api/2fa/status'));
+
+  await expect(response.json()).resolves.toEqual({
+    isEnabled: false,
+    isRequired: true,
+    requiredReason: 'global',
+  });
+  expect(response.status).toBe(200);
+});
+
+test('GET does not require 2FA when the encryption key is missing', async () => {
+  vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', '');
+
+  const response = await GET(new Request('http://localhost/api/2fa/status'));
+
+  expect(prismaMock.client.appSetting.findUnique).not.toHaveBeenCalled();
+  await expect(response.json()).resolves.toEqual({
+    isEnabled: false,
+    isRequired: false,
+    requiredReason: null,
+  });
+  expect(response.status).toBe(200);
+});
diff --git a/src/app/api/2fa/status/route.ts b/src/app/api/2fa/status/route.ts
index d7dc9a44f..57aa781bf 100644
--- a/src/app/api/2fa/status/route.ts
+++ b/src/app/api/2fa/status/route.ts
@@ -1,6 +1,7 @@
 import prisma from '@/lib/prisma';
 import { parseRequest } from '@/lib/request';
 import { json } from '@/lib/response';
+import { isTwoFactorConfigured } from '@/lib/two-factor/crypto';
 
 export async function GET(request: Request) {
   const { auth, error } = await parseRequest(request);
@@ -18,6 +19,11 @@ export async function GET(request: Request) {
   const twoFactor = await prisma.client.twoFactorAuth.findUnique({ where: { userId } });
   const isEnabled = twoFactor?.isEnabled ?? false;
 
+  // 2FA cannot be set up without an encryption key, so it is never required
+  if (!isTwoFactorConfigured()) {
+    return json({ isEnabled, isRequired: false, requiredReason: null });
+  }
+
   // Globally required
   const globalSetting = await prisma.client.appSetting.findUnique({
     where: { key: 'twoFactorRequiredGlobal' },
diff --git a/src/components/messages.ts b/src/components/messages.ts
index cc0d69d4b..b717200d4 100644
--- a/src/components/messages.ts
+++ b/src/components/messages.ts
@@ -506,5 +506,6 @@ export const messages: Record<string, string> = {
   twoFactorErrorAlreadyEnabled: 'message.two-factor-error-already-enabled',
   twoFactorErrorNotEnabled: 'message.two-factor-error-not-enabled',
   twoFactorErrorNoPendingSetup: 'message.two-factor-error-no-pending-setup',
+  twoFactorErrorNotConfigured: 'message.two-factor-error-not-configured',
   replayMinDurationDescription: 'message.replay-min-duration-description',
 };
diff --git a/src/components/modals/TwoFactorSetupModal.tsx b/src/components/modals/TwoFactorSetupModal.tsx
index 75bd01f19..4277b18f2 100644
--- a/src/components/modals/TwoFactorSetupModal.tsx
+++ b/src/components/modals/TwoFactorSetupModal.tsx
@@ -58,7 +58,7 @@ interface TwoFactorSetupModalProps {
 }
 
 export function TwoFactorSetupModal({ required, onClose }: TwoFactorSetupModalProps) {
-  const { t, labels, messages } = useMessages();
+  const { t, labels, messages, getErrorMessage } = useMessages();
   const [qrCodeDataUrl, setQrCodeDataUrl] = useState<string | null>(null);
   const [manualKey, setManualKey] = useState<string | null>(null);
   const [otpValue, setOtpValue] = useState('');
@@ -79,7 +79,7 @@ export function TwoFactorSetupModal({ required, onClose }: TwoFactorSetupModalPr
           setQrCodeDataUrl(data.qrCodeDataUrl);
           setManualKey(data.manualKey);
         },
-        onError: () => setError(t(messages.error)),
+        onError: (err: any) => setError(getErrorMessage(err) || t(messages.error)),
       },
     );
   }, []);
@@ -92,7 +92,7 @@ export function TwoFactorSetupModal({ required, onClose }: TwoFactorSetupModalPr
       const data: any = await confirm({ token });
       setBackupCodes(data.backupCodes);
     } catch (err: any) {
-      setError(err.message || t(messages.error));
+      setError(getErrorMessage(err) || t(messages.error));
     }
   };
 
diff --git a/src/lib/response.ts b/src/lib/response.ts
index 4c3f071a7..c3e2dbd68 100644
--- a/src/lib/response.ts
+++ b/src/lib/response.ts
@@ -54,6 +54,15 @@ export function notFound(error?: Record<string, any>) {
   );
 }
 
+export function serviceUnavailable(error?: Record<string, any>) {
+  return Response.json(
+    {
+      error: { message: 'Service unavailable', code: 'service-unavailable', status: 503, ...error },
+    },
+    { status: 503 },
+  );
+}
+
 export function serverError(error?: unknown) {
   if (error && typeof error !== 'string') {
     // eslint-disable-next-line no-console
diff --git a/src/lib/two-factor/crypto.test.ts b/src/lib/two-factor/crypto.test.ts
index 94f74ba7c..9f6f4d87e 100644
--- a/src/lib/two-factor/crypto.test.ts
+++ b/src/lib/two-factor/crypto.test.ts
@@ -51,3 +51,31 @@ describe('encryptSecret/decryptSecret', () => {
     vi.unstubAllEnvs();
   });
 });
+
+describe('isTwoFactorConfigured', () => {
+  test('returns true with a valid key', async () => {
+    vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', KEY);
+    vi.resetModules();
+    const { isTwoFactorConfigured } = await import('./crypto');
+
+    expect(isTwoFactorConfigured()).toBe(true);
+
+    vi.unstubAllEnvs();
+  });
+
+  test('returns false when the key is missing or invalid', async () => {
+    vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', '');
+    vi.resetModules();
+    const { isTwoFactorConfigured } = await import('./crypto');
+
+    expect(isTwoFactorConfigured()).toBe(false);
+
+    vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', 'too-short');
+    expect(isTwoFactorConfigured()).toBe(false);
+
+    vi.stubEnv('TWO_FACTOR_ENCRYPTION_KEY', 'z'.repeat(64));
+    expect(isTwoFactorConfigured()).toBe(false);
+
+    vi.unstubAllEnvs();
+  });
+});
diff --git a/src/lib/two-factor/crypto.ts b/src/lib/two-factor/crypto.ts
index 3901351e4..097c8b26a 100644
--- a/src/lib/two-factor/crypto.ts
+++ b/src/lib/two-factor/crypto.ts
@@ -1,14 +1,20 @@
 import { createCipheriv, createDecipheriv, randomBytes } from 'crypto';
 
 const ALGORITHM = 'aes-256-gcm';
+const KEY_REGEX = /^[0-9a-fA-F]{64}$/;
+
+/** Checks that TWO_FACTOR_ENCRYPTION_KEY holds a valid 256-bit key, without throwing. */
+export function isTwoFactorConfigured(): boolean {
+  const hex = process.env.TWO_FACTOR_ENCRYPTION_KEY;
+  return !!hex && KEY_REGEX.test(hex);
+}
 
 /** Loads and validates the 256-bit encryption key from TWO_FACTOR_ENCRYPTION_KEY. */
 function getKey(): Buffer {
-  const hex = process.env.TWO_FACTOR_ENCRYPTION_KEY;
-  if (!hex || hex.length !== 64 || !/^[0-9a-fA-F]{64}$/.test(hex)) {
+  if (!isTwoFactorConfigured()) {
     throw new Error('TWO_FACTOR_ENCRYPTION_KEY is missing or invalid');
   }
-  return Buffer.from(hex, 'hex');
+  return Buffer.from(process.env.TWO_FACTOR_ENCRYPTION_KEY, 'hex');
 }
 
 /** Encrypts a TOTP secret using AES-256-GCM. Returns `ciphertext:iv:authTag` as hex. */