Nightly – mozillawiki static electricity images

Every day, Mozilla developers write code that is merged into a common code repository (mozilla-central) and every day that code is compiled so as to create a pre-release version of Firefox based on this code for testing purposes, this is what we call a Nightly build. Once this code matures, it is merged into stabilization repositories (Beta and Dev Edition) where that code will be polished until we reach a level of quality that allows us to ship a new final version of Firefox to hundreds of millions of people. This development process used to ship a new version of Firefox every 5 to 8 weeks is called the Train Model.

If you are a power-user, that you want to have access to features in developments months before they become mainstream, have tolerance for occasional functional regressions and are looking for an easy way to help Mozilla and Firefox development, you should use Nightly (ideally as your main browser but you can also use it alongside Firefox on the release channel or another browser).

Unlike Firefox on the Release channel, Nightly sends by default anonymized usage statistics, called Telemetry which helps us improve Firefox and track regressions on a daily basis. Just using Nightly and sending telemetry data is already of great help to all Mozilla developers as it allows them to get usage statistics on the features they work on.

Nightly gets an update twice a day (or night, depending on your timezone), building starts at 10:00 and 22:00 UTC, usually builds are available one hour or two later. That means that there is an update in the morning for The Americas and another one for EMEA/Asia

If you don’t apply this update within 12 hours, a dialog box will pop up asking you to do so. If you want this dialog to show up later than 12h, in about:config change the app.update.promptWaitTime value from 43200 to a higher value, 86400 for 24 hours for example.

This activity has great potential to make an impact by increasing overall involvement in Nightly, simply by introducing community to tasks that they can engage in related to Nightly. Finding and filing issues early in the cycle means by the time Firefox gets to release, the code is in good shape.

First of all, thank you for doing that! Bugs reported early are also more easy to fix or back out than bugs reported weeks or months after the code was written, simply because developers just wrote it and have all of it fresh in their memory.

Don’t hesitate to ask experienced Nightly users (staff or employees) to help you file the bug in the #nightly IRC channel if you are unsure about the process or if English is not your native language and want to make sure your bug description is understandable.

Once you have filed the bug, you may get questions from bug triagers (people that enrich existing bug reports with useful metadata and try to get the right dev in front of the right issue) or developers that are trying to reproduce your bug using your configuration or the steps to reproduce what you experienced – watch your mailbox for such messages!

Some websites do not work in Firefox not because of a Firefox bug but because the site is restricting (intentionally or not) their audience to users of a specific browser. This is what we call a Web Compatibility issue. Since these issues can also affect other browsers than Firefox, web compatibility reports are filed in a separate bug tracker at

This will open the profile manager. Here, create a new profile with the name you want, and uncheck the checkbox saying "Use the selected profile without asking at startup", so that at every Firefox start you can choose the profile you want and corresponding to either your Nightly or Stable Firefox.

You don’t have to compile anything, just unarchive the tar.bz2 file into your /home or your /opt folder if you want to make it available to all the accounts on your machine and launch the firefox file from your shell. If you decide to install Firefox Nightly outside of your Home, such as in /opt/firefoxnightly, don’t forget to give this folder the same rights as your user otherwise it won’t auto-update:

If you want to create a Launcher for your app, you will need to create a .desktop file, here is on our blog an article about it for Ubuntu and Unity: Getting Firefox Nightly to stick to Ubuntu’s Unity Dock Is Nightly available as a .deb/.rpm?

If Open Source guerrilla community marketing is something you would like to get involved with and Nightly works great for you, maybe you could promote it to other power-users in your personal or professional networks, getting more users across the globe would help us catch more regressions, get more technical feedback and would allow us to ship a better browser.

Some of them are very easy, such as retweeting interesting tweets from our @FirefoxNightly or sharing them on other social networks, some represent more work such as participating to a local open source convention and presenting Nightly or organizing QA activities through Nightly via your local Mozilla community or Mozilla Club.

We are progressively setting up regional teams and Firefox Nightly Champions so as to have a per country or per language action which is often useful to solve issues such as language, timezones and regional specific sites. If you want to organize something online or offline related to Nightly, please contact Pascal Chevrel or Marcia Knous