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This is the issue tracker for Ember.js. The Ember.js community uses this site to collect and track bugs and discussions of new features. If you are having difficulties using Ember.js or have a question about usage, please ask a question on Stack Overflow:, or by joining the community chat.

The Ember.js community is very active on Stack Overflow and most questions receive attention the same day they're posted:

Issue Labeling

Ember uses StandardIssueLabels for Github Issues.


Think you've found a bug or have a new feature to suggest? Let us know!

Reporting a Bug

  1. Update to the most recent master release if possible. We may have already fixed your bug.

  2. Search for similar issues. It's possible somebody has encountered this bug already.

  3. Provide Ember Twiddle demo that specifically shows the problem. This demo should be fully operational with the exception of the bug you want to demonstrate. The more pared down, the better. If it is not possible to produce a fiddle, please make sure you provide very specific steps to reproduce the error. If we cannot reproduce it, we will close the ticket.

  4. Your issue will be verified. The provided example will be tested for correctness. The Ember team will work with you until your issue can be verified.

  5. Keep up to date with feedback from the Ember team on your ticket. Your ticket may be closed if it becomes stale.

  6. If possible, submit a Pull Request with a failing test. Better yet, take a stab at fixing the bug yourself if you can!

The more information you provide, the easier it is for us to validate that there is a bug and the faster we'll be able to take action.

Triaging policy

  • You might be requested to provide a reproduction or extra information. In that case, the issue will be labeled as Needs Submitter Response. If we did not get any response after seven days, we will ping you to remind you about it. We might close the issue if we do not hear from you after two weeks since the original notice.

  • If you submit a feature request as an issue, you will be invited to follow the instructions in this document and the issue will be closed

  • Issues that become inactive will be labeled accordingly to inform the original poster and Ember contributors that the issue should be closed since the issue is no longer actionable. The issue can be reopened at a later time if needed, e.g. becomes actionable again.

  • If possible, issues will be labeled to indicate the status or priority. For example, labels may have a prefix for Status: X, or Priority: X. Statuses may include: In Progress, On Hold. Priorities may include: High or Low.

Requesting a Feature

  1. Ember has an RFC process for feature requests. To begin the discussion either gather feedback on the emberjs/rfcs repository. Or, draft an Ember RFC

    • Use RFC pull request for well formed ideas.
    • Use RFC issues to propose a rough idea, basically a great place to test the waters.
  2. Provide a clear and detailed explanation of the feature you want and why it's important to add. Keep in mind that we want features that will be useful to the majority of our users and not just a small subset. If you're just targeting a minority of users, consider writing an add-on library for Ember.

  3. If the feature is complex, consider writing an Ember RFC document. If we do end up accepting the feature, the RFC provides the needed documentation for contributors to develop the feature according the specification accepted by the core team.

  4. After discussing the feature you may choose to attempt a Pull Request. If you're at all able, start writing some code. We always have more work to do than time to do it. If you can write some code then that will speed the process along.

In short, if you have an idea that would be nice to have, create an issue on the emberjs/rfcs repo. If you have a question about requesting a feature, start a discussion at

Building Ember.js

Building Ember.js is a quick process:

# clone the latest ember.js directory from github
 - git clone

# cd to the cloned ember.js directory
 - cd ember.js

# ensure Node.js and yarn are installed

# build ember.js
 - yarn install
 - yarn build

Using Custom Builds in an Ember CLI App

While testing custom behavior (maybe that you'd like to write an RFC for...), here's how you'd use a local custom build with an Ember app to test out the custom build:

# cd to the directory from Building Ember.js (above)
cd ember.js
yarn link
yarn start

# in a new terminal
cd ../your-app-directory/
yarn link ember-source

How to Run Unit Tests

Pull requests should pass the Ember.js unit tests. Do the following to run these tests.

  1. Follow the setup steps listed above under Building Ember.js.

  2. To start the development server, run yarn start.

  3. To run all tests, visit http://localhost:4200/.

  4. To test a specific package, visit http://localhost:4200/tests/index.html?package=PACKAGE_NAME. Replace PACKAGE_NAME with the name of the package you want to test. For example:

To test multiple packages, you can separate them with commas.

From the CLI

Run yarn test to run a basic test suite or run TEST_SUITE=all yarn test to run a more comprehensive suite.

From ember-cli

  1. ember test --server

  2. Connect the browsers you want.

To run a specific browser, you can use the --launch flag

  • ember test --server --launch SL_Firefox_Current
  • ember test --launch SL_Firefox_Current
  • ember test --launch SL_Firefox_Current,Chrome

To test multiple launchers, you can separate them with commas.

Pull Requests

We love pull requests. Here's a quick guide:

  1. Fork the repo.

  2. Run the tests. We only take pull requests with passing tests, and it's great to know that you have a clean slate: yarn install && yarn test. (To see tests in the browser, run yarn start and open http://localhost:4200/tests/index.html.)

  3. Add a test for your change. Only refactoring and documentation changes require no new tests. If you are adding functionality or fixing a bug, we need a test! If your change is a new feature, please wrap it in a feature flag.

  4. Make sure to check out the JavaScript Style Guide and ensure that your code complies with the rules. If you missed a rule or two, don't worry, our tests will warn you.

  5. Make the test pass.

  6. Commit your changes. Please use an appropriate commit prefix. If your pull request fixes an issue specify it in the commit message. Some examples:

[DOC beta] Update for commit prefixes
[FEATURE query-params-new] Message
[BUGFIX beta] Message
[SECURITY CVE-111-1111] Message

For more information about commit prefixes see the appendix.

  1. Push to your fork and submit a pull request. Please provide us with some explanation of why you made the changes you made. For new features make sure to explain a standard use case to us.

We try to be quick about responding to tickets but sometimes we get a bit backlogged. If the response is slow, try to find someone on IRC (#emberjs) to give the ticket a review.

Some things that will increase the chance that your pull request is accepted, taken straight from the Ruby on Rails guide:

  • Use Ember idioms and helpers
  • Include tests that fail without your code, and pass with it
  • Update the documentation, the surrounding one, examples elsewhere, guides, whatever is affected by your contribution


  • Two spaces, no tabs.
  • No trailing whitespace. Blank lines should not have any space.
  • a = b and not a=b.
  • Follow the conventions you see used in the source already.

Inline Documentation Guidelines:

All inline documentation is written using YUIDoc. Follow these rules when updating or writing new documentation:

  1. All code blocks must be fenced
  2. All code blocks must have a language declared
  3. All code blocks must be valid code for syntax highlighting
  4. All examples in code blocks must be aligned
  5. Use two spaces between the code and the example: foo(); // result
  6. All references to code words must be enclosed in backticks
  7. Prefer a single space between sentences
  8. Reference Ember.js as Ember.
  9. Wrap long markdown blocks > 80 characters
  10. Don't include blank lines after @param definitions

Code words are:

  • thisPropertyName
  • Global.Class.attribute
  • thisFunction()
  • true, false, null, undefined (when referring to programming values)
  • references to other properties/methods

And in case we didn't emphasize it enough: we love tests!

NOTE: Partially copied from

CI (Github Actions) Tests

We use GitHub Actions to test each PR before it is merged.

When you submit your PR (or later change that code), a CI build will automatically be kicked off. A note will be added to the PR, and will indicate the current status of the build.

Within the CI build, you can see that we (currently) run six different test suites.

  • The each-package test suite is closest to what you normally run locally on your machine.
  • The build-tests EMBER_ENV=production... test suite runs tests against a production build.
  • The browserstack test suite runs tests against various supported browsers.

Common CI Build Issues

Production Build Failures

If your build is failing on the 'production' suite, you may be relying on a debug-only function that does not even exist in a production build (Ember.warn, Ember.deprecate, Ember.assert, etc.). These will pass on the 'each-package' suite (and locally) because those functions are present in development builds.

There are helpers for many of these functions, which will resolve this for you: expectDeprecation, expectAssertion, etc. Please use these helpers when dealing with these functions.

If your tests can't aren't covered a helper, one common solution is the use of DEBUG flag. Wrapping the debug-only dependent test in a check of this flag will cause that test to not be run in the prod test suite:

import { DEBUG } from '@glimmer/env';

if (DEBUG) {
  // Development-only test goes here

Note: before using this approach, please be certain your test is really depending on a debug-only function and not truly failing in production.

To recreate this build environment locally:

  • Run ember serve --environment=production in a terminal (takes much much longer than a default ember s)
  • Browse to localhost:4200/tests/index.html?dist=prod&prod=true

Single Unexplained Test Suite Failure

Sometimes a single test suite will fail, without giving any indication of a real error.

  • Try to recreate the test environment locally (see above for production builds)
  • Restart all the test suites on CI by doing another push
  • Ask a repo collab to restart that single test suite


Commit Tagging

All commits should be tagged. Tags are denoted by square brackets ([]) and come at the start of the commit message.

Bug Fixes

In general bug fixes are pulled into the beta branch. As such, the prefix is: [BUGFIX beta]. If a bug fix is a serious regression that requires a new patch release, [BUGFIX release] can be used instead.

For bugs related to canary features, follow the prefixing rules for features.

The vast majority of bug fixes apply to the current stable or beta releases, so submit your PR against emberjs:master with one of the above mentioned BUGFIX tags. (In the unusual case of a bug fix specifically for a past release, tag for that release [BUGFIX release-1-13] and submit the PR against the stable branch for that release: emberjs:stable-1-13.)


Cleanup commits are for removing deprecated functionality and should be tagged as [CLEANUP beta].


All additions and fixes for features in canary should be tagged as [FEATURE name] where name is the same as the flag for that feature.


Documentation commits are tagged as [DOC channel] where channel is canary, beta, or release. If no release is provided canary is assumed. The channel should be the most stable release that this documentation change applies to.


Security commits will be tagged as [SECURITY cve]. Please do not submit security related PRs without coordinating with the security team. See the Security Policy for more information.


In general almost all commits should fall into one of these categories. In the cases where they don't please submit your PR untagged. An Ember contributor will let you know if tagging is required.