This page covers the basic steps needed to build a bleeding-edge, development version of Thunderbird 60 or later. For Thunderbird up to 59, see the old build documentation. For additional, more detailed information, see the build documentation.
- At least 4 GB of RAM. 8 GB or more is recommended. While you can build Thunderbird on older hardware it can take quite a bit of time to compile on slower machines with less RAM.
- Good internet connection for the initial source download.
Depending on your Operating System you will need to carry out a different process to prepare your machine. So firstly complete the instructions for your OS and then continue following these build instructions.
On Windows: check that the MAPI header files from https://www.microsoft.com/en-us/download/details.aspx?id=12905 are installed because the MAPI header files (except one) are not bundled with Visual Studio 2017 (Windows SDK 10). You should copy the header files to a Windows SDK include directory so that the build process will find the files, that is
C:\Program Files (x86)\Windows Kits\10\Include\10.0.nnnnn.0\shared respectively, where
nnnnn is the highest number present on the system. As of April 2019, 10.0.17134.0 is needed to compile Thunderbird. Assuming standard installation loations, copy these 17 files to
C:\Program Files (x86)\Windows Kits\10\Include\10.0.17134.0\shared.
18/10/2010 16:11 7,334 MAPIAux.h 02/06/2009 17:02 7,938 MAPICode.h 02/06/2009 17:02 22,960 MAPIDbg.h 02/06/2009 17:02 84,644 MAPIDefS.h 02/06/2009 17:02 27,840 MAPIForm.h 02/06/2009 17:02 11,880 MAPIGuid.h 02/06/2009 17:02 2,648 MAPIHook.h 02/06/2009 17:02 5,359 MAPINls.h 02/06/2009 17:02 2,743 MAPIOID.h 02/06/2009 17:02 32,978 MAPISPI.h 02/06/2009 17:02 54,395 MAPITags.h 02/06/2009 17:02 26,467 MAPIUtil.h 02/06/2009 17:02 97,301 MAPIVal.h 02/06/2009 17:02 9,334 MAPIWin.h 02/06/2009 17:02 1,906 MAPIWz.h 02/06/2009 17:02 18,277 MAPIX.h 02/06/2009 17:02 5,012 MSPST.h
Do NOT copy
MAPI.h, it is already in
C:\Program Files (x86)\Windows Kits\10\Include\10.0.17134.0\um\MAPI.h
Get the source
Get the latest Mozilla source code from Mozilla's
mozilla-central Mercurial code repository, and check it out into a local directory
source/ (or however you want to call it). Then, get the latest Thunderbird source code from Mozilla's
comm-central Mercurial code repository. It now needs to be placed inside the Mozilla source code, in a directory named
comm/ (this is inverse from Thunderbird 59 and earlier):
hg clone https://hg.mozilla.org/mozilla-central source/ cd source/ hg clone https://hg.mozilla.org/comm-central comm/
The source code requires 3.6GB of free space or more and additionally 5GB or more for default build. Instead of using
hg clone, you can follow these instructions on downloading and "unpacking" a Mercurial bundle.
Warning: The page Getting comm-central Source Code Using Mercurial [en-US] is 99% out of date! Only useful content is working with Github.
To build Thunderbird, you need to add a file named
mozconfig to the root directory of the mozilla-central checkout that contains the following line:
You can create a file with this line by doing this in the
echo 'ac_add_options --enable-application=comm/mail' > mozconfig
If you omit this line, the build system will build Firefox instead. Other build configuration options can be added to this file, although it's strongly recommended that you only use options that you fully understand. For example, to create a debug build instead of a release build, that file would also contain the line:
Each of these
ac_add_options entries needs to be on its own line.
For more on configuration options, see the page Configuring build options. Note that if you use an MOZ_OBJDIR it cannot be a sibling folder to your source directory. Use an absolute path to be sure!
To also build Lightning when building Thunderbird
Add the following line to your
To add that line you can do this in the
echo 'ac_add_options --enable-calendar' >> mozconfig
Before you start, make sure that the version you checked out is not busted. For hg tip, you should see green Bs on https://treeherder.mozilla.org/#/jobs?repo=comm-central
To start the build, cd into the source directory, and run:
mach is our command-line tool to streamline common developer tasks. See the mach article for more.
Building can take a significant amount of time, depending on your system, OS, and chosen build options. Linux builds on a fast box may take under 15 minutes, but Windows builds on a slow box may take several hours. Tips for making builds faster.
The executable will be at the location listed under Running below.
To run your build, you can use
There are various command line parameters you can add, e.g. to specify a profile.
Various temporary files, libraries, and the Thunderbird executable will be found in your object directory (under
comm-central/), which is prefixed with
obj-. The exact name depends on your system and OS. For example, a Mac user may get an object directory name of
The Thunderbird executable in particular, and its dependencies are located under the
dist/bin folder under the object directory. To run the executable from your
comm-central working directory:
How to update and build again
In your source directory:
hg pull -u cd comm hg pull -u cd ..
or same commands shorter:
hg pull -u; (cd comm; hg pull -u)
Then just re-run the mach command above. This will only recompile files that changed, but it's still a long haul.
To build after making changes, run
again. This will only rebuild what is necessary for these changes. It is also possible to rebuild specifically.
If you changed C or C++ files, run:
./mach build binaries
./mach build path/to/dir
This is the tricky bit since you need to specify the directory that installs the files, which may be a parent directory of the changed file's directory. For example, to just rebuild the Lightning calendar extension:
./mach build comm/calendar/lightning
For all other changes run the full rebuild:
- Check comm-central on Treeherder for known failures at the time you pulled the code. The current status of the trunk can also be checked at https://treestatus.mozilla.org/
- If the trunk is broken (i.e. closed), you may wish to consider building one of the branches (to pull the source code from a branch, just replace the url to the repository in the hg clone instruction).
- Check to make sure that the path in which you placed the source code has no spaces, and is not too long.
- Searched the bug database for issues relating to your problem (e.g., platform-specific issues).
- Try asking in mozilla.dev.builds - include details of what is in your mozconfig, and what the actual error is.
- Check if your mozilla/ is a symlink. A symlink there is not supported.
- Check for
@TOPSRCDIR@or relative paths in your mozconfig. Those have caused several problems historically and tend to be poorly tested when the build system changes.
- If on Windows you get link errors like "LNK1102: out of memory" or "LNK1318: Unexpected PDB error; OK (0)", try deleting the largest .PDB files before rushing out the door to buy more RAM. Clobbering (see below) will also remove those files.
- Try with a clean obj-dir. You can clean out previous build artefacts using