diff --git a/api/server/services/AppService.js b/api/server/services/AppService.js
index 63c136704f2..b62d274d53a 100644
--- a/api/server/services/AppService.js
+++ b/api/server/services/AppService.js
@@ -12,7 +12,7 @@ const paths = require('~/config/paths');
 const AppService = async (app) => {
   /** @type {TCustomConfig}*/
   const config = (await loadCustomConfig()) ?? {};
-  const socialLogins = config.registration.socialLogins ?? [
+  const socialLogins = config?.registration?.socialLogins ?? [
     'google',
     'facebook',
     'openid',
diff --git a/api/server/services/AppService.spec.js b/api/server/services/AppService.spec.js
new file mode 100644
index 00000000000..1f3f2245bec
--- /dev/null
+++ b/api/server/services/AppService.spec.js
@@ -0,0 +1,51 @@
+const { FileSources } = require('librechat-data-provider');
+
+const AppService = require('./AppService');
+
+jest.mock('./Config/loadCustomConfig', () => {
+  return jest.fn(() =>
+    Promise.resolve({
+      registration: { socialLogins: ['testLogin'] },
+      fileStrategy: 'testStrategy',
+    }),
+  );
+});
+jest.mock('./Files/Firebase/initialize', () => ({
+  initializeFirebase: jest.fn(),
+}));
+
+describe('AppService', () => {
+  let app;
+
+  beforeEach(() => {
+    app = { locals: {} };
+    process.env.CDN_PROVIDER = undefined;
+  });
+
+  it('should correctly assign process.env and app.locals based on custom config', async () => {
+    await AppService(app);
+
+    expect(process.env.CDN_PROVIDER).toEqual('testStrategy');
+
+    expect(app.locals).toEqual({
+      socialLogins: ['testLogin'],
+      fileStrategy: 'testStrategy',
+      paths: expect.anything(),
+    });
+  });
+
+  it('should initialize Firebase when fileStrategy is firebase', async () => {
+    require('./Config/loadCustomConfig').mockImplementationOnce(() =>
+      Promise.resolve({
+        fileStrategy: FileSources.firebase,
+      }),
+    );
+
+    await AppService(app);
+
+    const { initializeFirebase } = require('./Files/Firebase/initialize');
+    expect(initializeFirebase).toHaveBeenCalled();
+
+    expect(process.env.CDN_PROVIDER).toEqual(FileSources.firebase);
+  });
+});