Linux sequoia 4.3.0-rc5 [#80](/issue/ValveSoftware/steam-for-linux/80) SMP PREEMPT Mon Oct 12 13:46:00 CDT 2015 x86_64 GNU/Linux
nvidia-settings: version 358.16 (buildmeister@swio-display-x64-rhel04-12) Mon Nov 16 19:58:01 PST 2015

I launch steam from dmenu, enter my password, authenticate with mobile guard, then it closes. This just started happening today. I haven't changed anything on my system since several days ago, before it started doing this.

This happens with STEAM_RUNTIME=1 as well.

Running Steam on arch rolling 64-bit
STEAM_RUNTIME is disabled by the user
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
Assert( Assertion Failed: descs.Count() >= 1 ):../vgui_surfacelib/FontManager.cpp:276

Installing breakpad exception handler for appid(steam)/version(1454445843)
[0203/084300:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
[0203/084300:ERROR:browser_main_loop.cc(203)] Running without the SUID sandbox! See https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment for more information on developing with the sandbox on.
crash_20160203084300_6.dmp[18185]: Uploading dump (out-of-process)
/tmp/dumps/crash_20160203084300_6.dmp
../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
[0203/084300:INFO:audio_manager_pulse.cc(257)] Failed to connect to the context.  Error: Connection refused
Installing breakpad exception handler for appid(steamwebhelper)/version(20160202111919)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454445843)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454445843)
Installing breakpad exception handler for appid(steamwebhelper)/version(20160202111919)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454411959)
[0203/084300:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Created shared memory when not owner SteamController_Shared_mem
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
PulseAudio connect failed (used only for Mic Volume Control) with error: Access denied
Generating new string page texture 7: 128x256, total string texture memory is 131.07 KB
Generating new string page texture 8: 48x256, total string texture memory is 180.22 KB
Generating new string page texture 9: 256x256, total string texture memory is 442.37 KB
crash_20160203084300_6.dmp[18185]: Finished uploading minidump (out-of-process): success = yes
crash_20160203084300_6.dmp[18185]: response: CrashID=bp-9ee4909d-e00b-47c6-8bcb-ad34e2160203
crash_20160203084300_6.dmp[18185]: file ''/tmp/dumps/crash_20160203084300_6.dmp'', upload yes: ''CrashID=bp-9ee4909d-e00b-47c6-8bcb-ad34e2160203''
Generating new string page texture 10: 8x256, total string texture memory is 450.56 KB
Generating new string page texture 11: 16x256, total string texture memory is 466.94 KB
Generating new string page texture 12: 24x256, total string texture memory is 491.52 KB
Generating new string page texture 13: 32x256, total string texture memory is 524.29 KB
Generating new string page texture 14: 64x256, total string texture memory is 589.82 KB
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
Installing breakpad exception handler for appid(steam)/version(1454445843)
assert_20160203084258_1.dmp[18665]: Uploading dump (out-of-process)
/tmp/dumps/assert_20160203084258_1.dmp
/var/heap/.local/share/Steam/steam.sh: line 756: 18126 Segmentation fault      $STEAM_DEBUGGER "$STEAMROOT/$STEAMEXEPATH" "$@"
assert_20160203084258_1.dmp[18665]: Finished uploading minidump (out-of-process): success = yes
assert_20160203084258_1.dmp[18665]: response: CrashID=bp-ce9ed10f-c9f8-4eb9-9ad9-c05b82160203
assert_20160203084258_1.dmp[18665]: file ''/tmp/dumps/assert_20160203084258_1.dmp'', upload yes: ''CrashID=bp-ce9ed10f-c9f8-4eb9-9ad9-c05b82160203''