Building on Win10 ends with the following error:

0:52.78 Adding make options from c:\src\mozilla.org\mozilla-central2\.mozconfig
    AUTOCLOBBER=1
    MOZ_OBJDIR=c:/src/mozilla.org/mozilla-central2/obj-x86_64-pc-mingw32
    OBJDIR=c:/src/mozilla.org/mozilla-central2/obj-x86_64-pc-mingw32
    FOUND_MOZCONFIG=c:/src/mozilla.org/mozilla-central2/.mozconfig
    export FOUND_MOZCONFIG
 0:52.82 c:\mozilla-build\bin\mozmake.EXE -f client.mk -s
 0:55.64 Error running mach:
 0:55.64     ['--log-no-times', 'artifact', 'install']
 0:55.64 The error occurred in code that was called by the mach command. This is either
 0:55.64 a bug in the called code itself or in the way that mach is calling it.
 0:55.64 You can invoke |./mach busted| to check if this issue is already on file. If it
 0:55.64 isn't, please use |./mach busted file| to report it. If |./mach busted| is
 0:55.64 misbehaving, you can also inspect the dependencies of bug 1543241.
 0:55.65 If filing a bug, please include the full output of mach, including this error
 0:55.65 message.
 0:55.65 The details of the failure are as follows:
 0:55.65 TypeError: environment can only contain strings
 0:55.65   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild/mozbuild/artifact_commands.py", line 143, in artifact_install
 0:55.65     return artifacts.install_from(source, distdir or self.distdir)
 0:55.65   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 1259, in install_from
 0:55.65     return self.install_from_recent(distdir)
 0:55.65   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 1179, in install_from_recent
 0:55.65     return self._install_from_hg_pushheads(hg_pushheads, distdir)
 0:55.66   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 1158, in _install_from_hg_pushheads
 0:55.66     for trees, hg_hash in hg_pushheads:
 0:55.66   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 1037, in _find_pushheads
 0:55.66     last_revs = self._get_recent_public_revisions()
 0:55.66   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 998, in _get_recent_public_revisions
 0:55.66     cwd=self._topsrcdir).splitlines()
 0:55.66   File "c:/src/mozilla.org/mozilla-central2\python/mozbuild\mozbuild\artifacts.py", line 887, in run_hg
 0:55.66     **kwargs)
 0:55.66   File "c:\mozilla-build\python\lib\subprocess.py", line 216, in check_output
 0:55.66     process = Popen(stdout=PIPE, *popenargs, **kwargs)
 0:55.66   File "c:\mozilla-build\python\lib\subprocess.py", line 394, in __init__
 0:55.67     errread, errwrite)
 0:55.67   File "c:\mozilla-build\python\lib\subprocess.py", line 644, in _execute_child
 0:55.67     startupinfo)
 0:55.67 mozmake.EXE[3]: *** [Makefile:159: recurse_artifact] Error 1
 0:55.67 mozmake.EXE[2]: *** [c:/src/mozilla.org/mozilla-central2/config/recurse.mk:34: artifact] Error 2
 0:55.67 mozmake.EXE[1]: *** [c:/src/mozilla.org/mozilla-central2/config/rules.mk:389: default] Error 2
 0:55.68 mozmake.EXE: *** [client.mk:125: build] Error 2
 0:55.70 0 compiler warnings present.

Honza

Bug 1578198 sounds similar.

Honza

To workaround the problem try backing out bug 1583234 (changeset e72742f591f8997ac73863ad321f66a353923076) locally.

Andrew, what's the way forward here, do we need to call ensure_subprocess_env whenever we touch environment variables now?

Yes calling that method should fix this. Though this issue predates the Python 3 migration and is why we historically defined env like env[b"FOO"] = b"bar".

Details: With Python 2 certain Windows environments (but not all) require env to be bytes in the subprocess module. But on Python 3 passing bytes into subprocess is an error. So ensure_subprocess_env will convert the environment into the proper format depending on Python version.

https://hg.mozilla.org/mozilla-central/rev/388f454a9d3d