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Ember 3.21 Released

Today the Ember project is releasing version 3.21 of Ember.js, Ember Data, and Ember CLI.

Version 3.20 of Ember is now promoted to LTS (Long Term Support). An LTS version of Ember continues to receive security updates for 9 release cycles (54 weeks) and bugfixes for 6 cycles (36 weeks). LTS releases typically occur every four minor versions. The previous LTS version of Ember was 3.16.

This release kicks off the 3.22 beta cycle for all sub-projects. We encourage our community (especially addon authors) to help test these beta builds and report any bugs before they are published as a final release in six weeks' time. The ember-try addon is a great way to continuously test your projects against the latest Ember releases.

You can read more about our general release process here:


Ember.js is the core framework for building ambitious web applications.

Changes in Ember.js 3.21

Ember.js 3.21 is an incremental, backwards compatible release of Ember with bugfixes, performance improvements, and minor deprecations.

New Features

Ember.js 3.21 introduced no new features.


Ember.js 3.21 introduced 1 deprecation.

  1. getWithDefault (both the function and class method) has been deprecated per RFC #554.

Deprecations are added to Ember.js when an API will be removed at a later date. Each deprecation has an entry in the deprecation guide describing the migration path to a more stable API. Deprecated public APIs are not removed until a major release of the framework.

Consider using the ember-cli-deprecation-workflow addon if you would like to upgrade your application without immediately addressing deprecations.

For more details on changes in Ember.js 3.21, please review the Ember.js 3.21.0 release page.

Ember Data

Ember Data is the official data persistence library for Ember.js applications.

Changes in Ember Data 3.21

Ember Data 3.21 release saw a few improvements to documentation and continuous integration.

New Features

Ember Data 3.21 introduced no new features.


Ember Data 3.21 introduced no deprecations.

For more details on changes in Ember Data 3.21, please review the
Ember Data 3.21.0 release page.

Ember CLI

Ember CLI is the command line interface for managing and packaging Ember.js applications.

Upgrading Ember CLI

You may upgrade Ember CLI easily using the ember-cli-update project:

npx ember-cli-update

This utility will help you to update your app or addon to the latest Ember CLI version. You will probably encounter merge conflicts, in which the default behavior is to let you resolve conflicts on your own. For more information on the ember-cli-update project, see the GitHub README.

While it is recommended to keep Ember CLI versions in sync with Ember and Ember Data, this is not required. After updating ember-cli, you can keep your current version(s) of Ember or Ember Data by editing package.json to revert the changes to the lines containing ember-source and ember-data.

Changes in Ember CLI 3.21

New Features

Ember CLI 3.21 introduced 2 new features.

  1. ember new --lang support has landed per RFC #635.

  2. ember-try configuration for addons has been updated. ember-lts-3.12 has been dropped from the default testing matrix. (Existing addons should consider this as a breaking change.) In addition, ember-lts-3.20 has been added to the default testing matrix.


Ember CLI 3.21 introduced no deprecations.

For more details on the changes in Ember CLI 3.21 and detailed upgrade
instructions, please review the Ember CLI 3.21.0 release page.

Thank You!

As a community-driven open-source project with an ambitious scope, each of these releases serves as a reminder that the Ember project would not have been possible without your continued support. We are extremely grateful to our contributors for their efforts.

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