Ember 3.5 Released

– By Melanie Sumner, Jen Weber, Chris Thoburn

Today the Ember project is releasing version 3.5 of Ember.js, Ember Data, and Ember CLI. Notable features include Ember CLI build performance improvements of up to 32% and new Ember Data powers for addon developers.

Additionally, versions 3.4 of Ember, Ember CLI, and Ember Data are now promoted to LTS, which stands for 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 for Ember was 2.18. 3.4 is the first LTS for Ember CLI and Ember Data.

This release kicks off the 3.6 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 3.5

Ember.js 3.5 is an incremental, backwards compatible release of Ember with bugfixes. It is common for minor releases to provide bugfixes that pave the way for release of new features in future releases. There are zero (0) new features, zero (0) deprecations, and two (2) small bugfixes in this version. Contributors to the Ember.js codebase itself should note that it now uses Typescript 3.0 internally.

Bugfixes (2).

For more details on changes in Ember.js 3.5, please review the Ember.js 3.5.0 release page.

Ember Data

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

Changes in Ember Data 3.5

This release cycle marks two major milestones for ember-data, an LTS release and the RecordData interfaces.


The first milestone is the release of 3.4 LTS, our very first LTS release! From here out, ember-data will follow the same LTS cycle and process as Ember.

New Features (1)


The second milestone is the release of 3.5 which marks the first release containing the new RecordData interfaces. RecordData gives addon developers much-needed API access with more confidence and stability. Many commonly requested features (improved dirty-tracking, fragments, alternative Models) are now possible or easier to implement in addons.

Landing RecordData required significant refactoring of the internals of ember-data, and is intended to allow us to deprecate and remove use of the private but intimate InternalModel API. Due to the nature of this change, we expect some applications may encounter regressions. This was the primary motivation for waiting to land this until after our first LTS. If you encounter issues upgrading from pre 3.5 versions to 3.5 or later, we recommend reporting them and making use of LTS until fixes are available.

We are tracking issues introduced by RecordData with the label record-data

We will also continue to target bugfixes for LTS, tracked by the label lts-target.

RecordData use with ModelFragments

While most community addons have been found to work with RecordData versions of ember-data, ember-data-model-fragments does not currently. If you use this addon, it is likely you will want to stay on ember-data 3.4 LTS until the community has released a version compatible with RecordData.

If you use ember-data-model-fragments, helping to refactor it to make use of RecordData (or supply bugfixes to ember-data if required) would be greatly appreciated.

Deprecations (0)

No new deprecations introduced in Ember Data 3.5.

For more details on Ember Data 3.5, please review the Ember Data 3.5.0 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 separately from Ember.js and Ember Data! To upgrade your projects using yarn run:

yarn upgrade ember-cli

To upgrade your projects using npm run:

npm install --save-dev ember-cli

After running the upgrade command, make sure to install (if you haven't already) ember-cli-update globally:

npm install -g ember-cli-update

This utility will help you to update your app or add-on 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.

Changes in Ember CLI 3.5

This release cycle marks a major milestone for ember-cli, an LTS release.


The milestone is the release of 3.4 LTS, our very first LTS release! From here out, ember-cli will follow the same LTS cycle and process as Ember.

New Features (3)

Upgraded to Broccoli v2.0.0! (1 of 3)

Broccoli is an asset pipeline used by Ember. For quite a long time, tools in the Ember Ecosystem relied on a fork of Broccoli. However, as of this release, Ember CLI now uses Broccoli 2.0 directly! See this Ember.js Times Reader's question to learn more about what makes Broccoli awesome and why it is used instead of Parcel or Webpack. Many thanks to contributors and maintainers of Broccoli who helped with the migration.

Build speed improvements up to 32% (2 of 3)

Thanks to migrating to Broccoli 2, Ember devs should see some speed improvements in their builds. Broccoli 2 allows Ember CLI to use the default system temp directory rather than a ./tmp directory local to a project folder. Depending on computer hardware, users may see up to 32% improvements in build time. The system temp directory on your computer has some optimizations in place that your apps now benefit from.

Migration to ember-qunit (3 of 3)

ember-cli-qunit was a very thin shim over ember-qunit. Ember CLI now uses ember-qunit directly as a dependency.

Deprecations (0)

No new deprecations introduced in Ember CLI 3.5.

For more details on the changes in Ember CLI 3.5 and detailed upgrade instructions, please review the Ember CLI 3.5.0 release page.

Thank You!

As a community-driven open-source project with an ambitious scope, each of these releases serve 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.