Can't confirm this issue on GNU\Linux Debian 8 'jessie' x86_64 with nVidia drivers 340.96

Same problem here on Arch Linux (linux 4.4.1, nvidia drivers 361.28):

/home/nicoulaj/.local/share/Steam/steam.sh: line 161: VERSION_ID: unbound variable
/home/nicoulaj/.local/share/Steam/steam.sh: line 161: VERSION_ID: unbound variable
Running Steam on arch  64-bit
/home/nicoulaj/.local/share/Steam/steam.sh: line 161: VERSION_ID: unbound variable
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1454620878)
Installing breakpad exception handler for appid(steam)/version(1454620878)
Installing breakpad exception handler for appid(steam)/version(1454620878)

(steam:14537): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",

(steam:14537): Gtk-WARNING **: Unable to locate theme engine in module_path: "adwaita",
/usr/share/themes/Adwaita/gtk-2.0/gtkrc:1163: error: unexpected identifier `direction', expected character `}'
Installing breakpad exception handler for appid(steam)/version(1454620878)
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 72: non-double matrix element
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 72: non-double matrix element
Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 80: saw unknown, expected number
[0228/144740:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
[0228/144740: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.
Installing breakpad exception handler for appid(steamwebhelper)/version(20160204122139)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454588499)
[0228/144740:ERROR:main_delegate.cc(777)] Could not load cef_extensions.pak
Installing breakpad exception handler for appid(steamwebhelper)/version(20160204122139)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454620878)
Installing breakpad exception handler for appid(steamwebhelper)/version(1454620878)
ICE default IO error handler doing an exit(), pid = 14537, errno = 11
[2016-02-28 14:47:40] Startup - updater built Feb  4 2016 12:22:08
Looks like steam didn't shutdown cleanly, scheduling immediate update check
[2016-02-28 14:47:40] Checking for update on startup
[2016-02-28 14:47:40] Checking for available updates...
[2016-02-28 14:47:40] Download skipped: /client/steam_client_ubuntu12 version 1454620878, installed version 1454620878
[2016-02-28 14:47:40] Nothing to do
[2016-02-28 14:47:40] Verifying installation...
[2016-02-28 14:47:40] Performing checksum verification of executable files
[2016-02-28 14:47:40] Verification complete
Assert( Assertion Failed: CFrameFunctionMgr::~CFrameFunctionMgr: non static FrameFunction[CHTTPClient::BFrameFuncHandleCompletedWorkItems] still registered ):framefunction.cpp:120

Installing breakpad exception handler for appid(steam)/version(1454620878)
crash_20160228144746_2.dmp[14566]: Uploading dump (out-of-process)
/tmp/dumps/crash_20160228144746_2.dmp
framefunction.cpp (120) : Assertion Failed: CFrameFunctionMgr::~CFrameFunctionMgr: non static FrameFunction[CHTTPClient::BFrameFuncHandleCompletedWorkItems] still registered
crash_20160228144746_2.dmp[14566]: Finished uploading minidump (out-of-process): success = yes
crash_20160228144746_2.dmp[14566]: response: CrashID=bp-e1d2064c-b104-442a-9e24-8fa2c2160228
crash_20160228144746_2.dmp[14566]: file ''/tmp/dumps/crash_20160228144746_2.dmp'', upload yes: ''CrashID=bp-e1d2064c-b104-442a-9e24-8fa2c2160228''

Fresh install (rm -rf ~/.local/share/Steam) does not solve the issue.

same here on a fresh gentoo build

Ubuntu 20.04 It was working fine untill today.

~/.local/share/Steam$ sudo ./steam.sh 
...

Do not run Steam Client as root user, it is potentially harmful and not necessary.
To run Steam Client simply type: steam