1 Building Firefox On Windows
2 ======================================
4 This document will help you get set up to build Firefox on your own
5 computer. Getting set up can take a while - we need to download a
6 lot of bytes! Even on a fast connection, this can take ten to fifteen
7 minutes of work, spread out over an hour or two.
9 If you'd prefer to build Firefox for Windows in a virtual machine,
10 you may be interested in the `Windows images provided by Microsoft
11 <https://developer.microsoft.com/en-us/windows/downloads/virtual-machines/>`_.
16 - **Memory:** 4GB RAM minimum, 8GB+ recommended.
17 - **Disk Space:** At least 40GB of free disk space.
18 - **Operating System:** Windows 10. It is advisable to have Windows Update be fully
19 up-to-date. See :ref:`build_hosts` for more information.
21 Recommended (For Windows 11 Users)
22 ----------------------------------
24 <https://learn.microsoft.com/en-us/windows/dev-drive/#how-to-set-up-a-dev-drive>`_.
28 - A Dev Drive has been shown to make Firefox builds and VCS operations 5-10% faster.
29 - This guide assumes no Dev Drive, so all instructions of ``C:\mozilla-source`` should be to your Dev Drive letter instead (eg: ``D:\mozilla-source``), as your ``C:\`` drive can never be a Dev Drive.
31 1. Install MozillaBuild
32 -----------------------
35 <https://ftp.mozilla.org/pub/mozilla/libraries/win32/MozillaBuildSetup-Latest.exe>`_.
37 Accept the default installation directory.
38 Windows may prompt you to "reinstall with the correct settings", which you
39 should click to accept.
41 When working with Firefox tooling, you'll need to do so from within the MozillaBuild
42 shell. You can start it by running ``C:\mozilla-build\start-shell.bat`` (you may want
43 to make a shortcut to this file so it's easier to start).
47 The MozillaBuild shell is a lot more like a Linux shell than the Windows ``cmd``. You can
48 learn more about it `here <https://wiki.mozilla.org/MozillaBuild>`_.
50 2. Bootstrap a copy of the Firefox source code
51 ----------------------------------------------
53 Now that your system is ready, we can download the source code and have Firefox
54 automatically download the other dependencies it needs. The below command
55 will download a lot of data (years of Firefox history!) then guide you through
56 the interactive setup process.
60 # Using the C:\mozilla-build\start-shell.bat shell from step 1:
64 wget https://hg.mozilla.org/mozilla-central/raw-file/default/python/mozboot/bin/bootstrap.py
68 When running ``bootstrap.py`` there will be a `UAC (User Account Control) prompt <https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/how-user-account-control-works>`_ for PowerShell after
69 selecting the destination directory for the source code clone. This is
70 necessary to add the Microsoft Defender Antivirus exclusions automatically. You
71 should select ``Yes`` on the UAC prompt, otherwise you will need
72 to :ref:`follow some manual steps below <Ensure antivirus exclusions>`.
76 To use ``git``, you can grab the source code in "git" form by running the
77 bootstrap script with the ``vcs`` parameter:
81 python3 bootstrap.py --vcs=git
83 This uses `Git Cinnabar <https://github.com/glandium/git-cinnabar/>`_ under the hood.
88 If you aren't modifying the Firefox backend, then select one of the
89 :ref:`Artifact Mode <Understanding Artifact Builds>` options. If you are
90 building Firefox for Android, you should also see the :ref:`GeckoView Contributor Guide <geckoview-contributor-guide>`.
92 .. _Ensure antivirus exclusions:
94 Ensure antivirus exclusions
95 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
97 Microsoft Defender Antivirus and some third-party antivirus products
98 are known to significantly degrade build times and sometimes even cause failed
99 builds (due to a "missing file"). This is usually because we have tests for
100 well-known security bugs that have code samples that antivirus software identifies
101 as a threat, automatically quarantining/corrupting the files.
103 To avoid this, add the following folders to your third-party antivirus exclusion list:
105 - The ``C:\mozilla-build`` folder.
106 - The directory where the Firefox code is (probably ``C:\mozilla-source``).
107 - The ``%USERPROFILE%/.mozbuild`` directory (probably ``C:\Users\<user>\.mozbuild``).
109 The ``bootstrap.py`` script attempts to add the above folders to the Microsoft
110 Defender Antivirus exclusion list automatically. You should check that they were
111 successfully added, but if they're missing you will need to `add the exclusions to
112 Microsoft Defender Antivirus manually
113 <https://support.microsoft.com/en-ca/help/4028485/windows-10-add-an-exclusion-to-windows-security>`_.
117 If you are using Mercurial and you're already missing files (you'll see them listed in ``hg status``), you can have them
118 brought back by reverting your source tree: ``hg update -C``.
120 If you are using Git and you're already missing files (you'll see them listed in ``git status``), you can have them brought back by discarding changes in your source tree: ``git restore .``.
125 Now that your system is bootstrapped, you should be able to build!
127 .. code-block:: shell
129 cd c:/mozilla-source/mozilla-unified
133 🎉 Congratulations! You've built your own home-grown Firefox!
134 You should see the following message in your terminal after a successful build:
136 .. code-block:: console
138 Your build was successful!
139 To take your build for a test drive, run: |mach run|
140 For more information on what to do now, see https://firefox-source-docs.mozilla.org/setup/contributing_code.html
142 You can now use the ``./mach run`` command to run your locally built Firefox!
144 If your build fails, please reference the steps in the `Troubleshooting section <#troubleshooting>`_.
149 Time to start hacking! You should join us on `Matrix <https://chat.mozilla.org/>`_,
150 say hello in the `Introduction channel
151 <https://chat.mozilla.org/#/room/#introduction:mozilla.org>`_, and `find a bug to
152 start working on <https://codetribute.mozilla.org/>`_.
153 See the :ref:`Firefox Contributors' Quick Reference` to learn how to test your changes,
154 send patches to Mozilla, update your source code locally, and more.
158 If you'd like to interact with Mach from a different command line environment
159 than MozillaBuild, there's experimental support for it described
160 :ref:`over here <Using Mach on Windows Outside MozillaBuild>`.
168 If you encounter a build error when trying to setup your development environment, please follow these steps:
169 1. Copy the entire build error to your clipboard
170 2. Paste this error on `paste.mozilla.org <https://paste.mozilla.org>`_ in the text area and change the "Expire in one hour" option to "Expire in one week". Note: it won't take a week to get help but it's better to have the snippet be around for a bit longer than expected.
171 3. Go to the `introduction channel <https://chat.mozilla.org/#/room/#introduction:mozilla.org>`__ and ask for help with your build error. Make sure to post the link to the paste.mozilla.org snippet you created!
173 MozillaBuild out-of-date
174 ~~~~~~~~~~~~~~~~~~~~~~~~
176 The build system expects that you're using the most-recent MozillaBuild release.
177 However, MozillaBuild doesn't auto-update. If you're running into local issues,
178 they may be resolved by `upgrading your MozillaBuild <https://wiki.mozilla.org/MozillaBuild>`_.
180 Spaces in folder names
181 ~~~~~~~~~~~~~~~~~~~~~~
183 **Firefox will not build** if the path to MozillaBuild or the Firefox source
184 contain **spaces** or other breaking characters such as pluses, quotation marks,
185 or metacharacters. The Visual Studio tools and SDKs are an exception - they may
186 be installed in a directory which contains spaces. It is strongly recommended
187 that you accept the default settings for all installation locations.
189 Quotation marks in ``PATH``
190 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
192 Quotation marks (") aren't translated properly when passed to MozillaBuild
193 sub-shells. Since they're not usually necessary, you should ensure they're
194 not in your ``PATH`` environment variable.
196 ``PYTHON`` environment variable
197 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
199 If ``PYTHON`` is set, the build may fail with the error: "``The system
200 cannot find the file specified``." Ensure that you aren't having
201 a ``PYTHON`` environment variable set.
206 If you happen to have Cygwin installed, its tools may erroneously be
207 used when building Firefox. Ensure that MozillaBuild directories (in
208 ``C:\mozilla-build\``) are before Cygwin directories in the ``PATH``
209 environment variable.