# v4 code migration: Updating configuration

This guide is part of the v4 code migration guide designed to help you migrate the code of a Strapi application from v3.6.x to v4.0.x.

Strapi v4 introduces several types of changes to configurations, which includes new files, moved or restructured files, and removed features. The following table gives a high-level overview of the changes, and you can click on a specific topic to read more information:

Configuration topic	Type of change in Strapi v4 vs. v3	File name in Strapi v4
Database	Changes to an existing Strapi v3 file	`database.js`
Server	Changes to an existing Strapi v3 file	`server.js`
Admin panel	New file in Strapi v4	`admin.js`
Middlewares	Changes to an existing Strapi v3 file	`middlewares.js`
CRON tasks	New file in Strapi v4	`cron-tasks.js`
API	Changes to an existing Strapi v3 file	`api.js`
Plugins	Changes to an existing Strapi v3 file	`plugins.js`
Bootstrap function	Now defined in the global `src/index.js` file	-
Custom functions folder	Feature removed from Strapi v4	-
Custom responses	Feature removed from Strapi v4	-

✏️ NOTE

This part of the code migration guide is not an exhaustive resource for Strapi v4 configurations, which are described in the configurations documentation.

# Database configuration

✋ CAUTION

MongoDB databases are no longer supported in Strapi v4. You need to migrate to a compatible SQL database to use Strapi v4.

Due to the complete rewrite of the database and query layers in Strapi v4, the entire structure of the database.js file has changed (see database configuration documentation). Multi-database support has been dropped, so there is no more defaultConnection key. Instead, in Strapi v4, the 2 main database configuration objects are:

connection, passed to the database connection manager package (i.e. Knex.js (opens new window)),
and settings for Strapi-specific settings.

✏️ NOTE

Strapi v4 does not abstract Knex.js key names so some key names are different in Strapi v3 and v4 (e.g. username in Strapi v3 is now user in Strapi v4) (see database configuration documentation).

Example of a Strapi v3 database configuration for PostgreSQL:

// path: ./config/database.js

module.exports = ({ env }) => ({
  defaultConnection: 'default',
  connections: {
    default: {
      connector: 'bookshelf',
      settings: {
        client: 'postgres',
        host: env('DATABASE_HOST', 'localhost'),
        port: env.int('DATABASE_PORT', 5432),
        database: env('DATABASE_NAME', 'strapi'),
        username: env('DATABASE_USERNAME', 'strapi'),
        password: env('DATABASE_PASSWORD', 'strapi'),
        schema: env('DATABASE_SCHEMA', 'public'), // Not Required
        ssl: {
          rejectUnauthorized: env.bool('DATABASE_SSL_SELF', false), // For self-signed certificates
        },
      },
      options: {},
    },
  },
});

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Example of a Strapi v4 database configuration for PostgreSQL:

// path: ./config/database.js

module.exports = ({ env }) => ({
  connection: {
    client: 'postgres',
    connection: {
      host: env('DATABASE_HOST', '127.0.0.1'),
      port: env.int('DATABASE_PORT', 5432),
      database: env('DATABASE_NAME', 'strapi'),
      user: env('DATABASE_USERNAME', 'strapi'),
      password: env('DATABASE_PASSWORD', 'strapi'),
      schema: env('DATABASE_SCHEMA', 'public'), // Not Required
      ssl: {
        rejectUnauthorized: env.bool('DATABASE_SSL_SELF', false), // For self-signed certificates
      },
    },
    debug: false,
  },
});

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# Server configuration

The server configuration in Strapi v4 is similar to Strapi v3, with the following exceptions:

All admin panel-related settings (i.e. admin.* keys) are in the admin.js file.
CRON tasks (configured with cron.* keys) can be directly referenced in the ./config/server.js or imported from any other custom files (see cron-tasks.js file).
app.keys is a new configuration option for the refactored session middleware and is used to create secure session keys.

Example of a Strapi v3 server configuration:

// path: ./config/server.js

module.exports = ({ env }) => ({
  host: env('HOST', '0.0.0.0'),
  port: env.int('PORT', 1337),
  admin: {
    // ...
  },
});

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Example of a Strapi v4 server configuration:

// path: ./config/server.js

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

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# Admin panel configuration

In Strapi v3, admin panel configuration is defined inside an admin object within the server.js configuration file.

In Strapi v4, the admin panel configuration is defined in ./config/admin.js (see project structure).

By default, in Strapi v4, only 2 keys are required in admin.js:

apiToken.salt is used as the salt key for the new API tokens feature,
auth.secret (previously located in the server.js file in Strapi v3) is used to encrypt JWTs for the admin panel.

The admin panel configuration documentation lists all the other available options.

Example of a Strapi v3 server.js admin configuration section:

// path: ./config/server.js

module.exports = ({ env }) => ({
  // ...
  admin: {
    auth: {
      secret: env('ADMIN_JWT_SECRET', '77b2c87dbab4e1697bec244226fbd1b3'),
    },
  },
});

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Example of a Strapi v4 admin.js configuration file:

// path: ./config/admin.js

module.exports = ({ env }) => ({
  apiToken: {
    salt: env('API_TOKEN_SALT', 'd9b0df66ff97a666027e665707b4e3e7'),
  },
  auth: {
    secret: env('ADMIN_JWT_SECRET', '77b2c87dbab4e1697bec244226fbd1b3'),
  },
});

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# Middlewares configuration

Middlewares in Strapi v4 have been entirely overhauled and the Strapi v3 configuration format (e.g. load order, before, and after keys) is replaced with a single array representing the loading order.

Middlewares configuration in Strapi v4 is defined in the ./config/middlewares.js file (plural file name, instead of middleware.js in Strapi v3).

Example of Strapi v3 middlewares configuration:

// path: ./config/middleware.js

module.exports = {
  //...
  settings: {
    cors: {
      origin: ['http://localhost', 'https://mysite.com', 'https://www.mysite.com'],
    },
  },
  // ...
};

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Example of Strapi v4 middlewares configuration:

Important: Various middlewares in this list are required. During configuration, replace the string with the object format (see middlewares configuration).

// path: ./config/middlewares.js

module.exports = [
  'strapi::errors',
  'strapi::security',
  {
    name: 'strapi::cors',
    config: {
      origin: ['http://localhost', 'https://mysite.com', 'https://www.mysite.com'],
    }
  },
  'strapi::poweredBy',
  'strapi::logger',
  'strapi::query',
  'strapi::body',
  'strapi::session',
  'strapi::favicon',
  'strapi::public',
];

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✏️ NOTE

In Strapi v4, security middlewares from Strapi v3 have been removed and replaced with koa-helmet (opens new window), which is a Koa.js wrapper for helmet (opens new window). This package replaces all security middlewares except for cors (see internal middlewares configuration reference).

# CRON tasks

In Strapi v3, CRON tasks could be defined in a ./config/functions/cron.js file.

In Strapi v4, the config/functions folder does not exist anymore, and CRON tasks can be defined:

in a separate file (e.g. ./config/cron-tasks.js)
or in the server.js file:
- either by directly declaring them here
- or by creating a custom file and requiring it in the server.js file.

# API configuration

The API configuration options are similar in Strapi v3 and v4, with the exception of the following keys:

rest.defaultLimit is 25 by default (instead of 100 in Strapi v3)
rest.maxLimit is 100 by default (instead of null in Strapi v3)
rest.prefix is a new API configuration option. Its default value is /api and can be changed to anything but /.

The API configuration is optional.

Example of a Strapi v3 API configuration:

// path: ./config/api.js

module.exports = ({ env }) => ({
  responses: {
    privateAttributes: ['created_at'],
  },
  rest: {
    defaultLimit: 100,
    maxLimit: 250,
  },
});

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Example of a Strapi v4 API configuration:

// path: ./config/api.js

module.exports = ({ env }) => ({
  responses: {
    privateAttributes: ['createdAt'],
  },
  rest: {
    prefix: '/v1',
    defaultLimit: 100,
    maxLimit: 250,
  },
});

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# Plugins configuration

✋ CAUTION

Strapi v3 plugins may not work with Strapi v4. If you are a plugin developer wanting to upgrade your plugin to Strapi v4, please refer to the plugin migration guide.

Plugins configuration in Strapi v4 include the ability to:

enable or disable a plugin,
and have custom resolve locations in addition to custom configuration options.

To migrate to Strapi v4, use the new enabled and resolve keys and move existing Strapi v3 custom configuration keys into a nested config object:

Example of a Strapi v3 plugins configuration:

module.exports = ({ env }) => ({
  // ...
  sentry: {
    dsn: env('SENTRY_DSN'),
    sendMetadata: true,
  },
  // ...
});

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Example of a Strapi v4 plugins configuration:

// path: ./config/plugins.js

module.exports = ({ env }) => ({
  sentry: {
    enabled: true,
    resolve: './src/plugins/my-sentry-fork',
    config: {
      dsn: env('SENTRY_DSN'),
      sendMetadata: true,
      myCustomSetting: false,
    },
  },
  graphql: {
    enabled: true,
    config: {
      defaultLimit: 10,
      maxLimit: 20,
    },
  },
});

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✏️ NOTE

For specific plugin configurations, please refer to the dedicated plugin's documentation.

# Custom functions folder

The config/functions folder and all of its content no longer exist in Strapi v4. The bootstrap.js file and CRON tasks have their own dedicated configuration options but global functions are no longer automatically added to the Strapi internal API.

When creating universal utility functions in Strapi v4, it's recommended to:

either create a plugin dedicated to holding those utility functions,
or build services that can be called from anywhere in the Strapi backend.

# Bootstrap function

The dedicated bootstrap.js file no longer exists in Strapi v4 and is now a global function combined with the new register function. bootstrap() and register() can be found in ./src/index.js (see functions documentation).

# Custom responses

Due to the standardization of the response and error handling structures in Strapi v4, it's no longer possible to customize the response structure or add custom response structures.

For custom error messages, please refer to the error handling documentation or the requests & responses documentation.

🤓 Next steps

Migrating the back end code of Strapi to v4 also requires to at least migrate the core features of the Strapi server, such as the dependencies, routes, controllers, services, and content-type schema.

← v4 migration guides Code migration - Dependencies - Strapi Developer Docs →