Trying to set up strapi and cloudinary I watched two videos and they are all OK, but I have an error, tell me why?

Middleware "strapi::session": App keys are required. Please set app.keys in config/server.js (ex: keys: ['myKeyA', 'myKeyB'])

plugins.js

module.exports = ({ env }) => ({
  // ...
  upload: {
    config: {
      provider: 'cloudinary',
      providerOptions: {
        cloud_name: env('CLOUDINARY_NAME'),
        api_key: env('CLOUDINARY_KEY'),
        api_secret: env('CLOUDINARY_SECRET'),
      },
      actionOptions: {
        upload: {},
        delete: {},
      },
    },
  },
  // ...
});

.env

HOST=0.0.0.0
PORT=1337
CLOUDINARY_NAME="my data"
CLOUDINARY_KEY="my data"
CLOUDINARY_SECRET="my data"
JWT_SECRET=my data

server.js

module.exports = ({ env }) => ({
  host: env('HOST', '0.0.0.0'),
  port: env.int('PORT', 1337),
  app: {
    keys: env.array('APP_KEYS'),
  },
});

middlewares.js

module.exports = [
  'strapi::errors',
  'strapi::security',
  'strapi::cors',
  'strapi::poweredBy',
  'strapi::logger',
  'strapi::query',
  'strapi::body',
  'strapi::session',
  'strapi::favicon',
  'strapi::public',
];

admin.js

module.exports = ({ env }) => ({
  auth: {
    secret: env('ADMIN_JWT_SECRET'),
  },
  apiToken: {
    salt: env('API_TOKEN_SALT'),
  },
});