Terminal output:

Running Steam on   64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number
[0430/005009:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Generating new string page texture 2: 48x256, total string texture memory is 49,15 KB
Generating new string page texture 3: 256x256, total string texture memory is 311,30 KB
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Adding licenses for the following package(s): 0, 25, 38, 39, 40, 41, 207, 218, 283, 418, 419, 420, 421, 434, 439, 469, 525, 675, 783, 1016, 1053, 1290, 1295, 1465, 1507, 1549, 2208, 2212, 2297, 2414, 2577, 4109, 4176, 4363, 4451, 4452, 4885, 6098, 6428, 6927, 6997, 7209, 7397, 7627, 7708, 7950, 8009, 8041, 8077, 8132, 8183, 8276, 8394, 8429, 8450, 8451, 8535, 8876, 8878, 11010, 11033, 11071, 11144, 11355, 11618, 11819, 11831, 11837, 11904, 12000, 12016, 12017, 12129, 12225, 12328, 12383, 12456, 12558, 13082, 13162, 13191, 13390, 13553, 13568, 13624, 13632, 13646, 13670, 13698, 14012, 14176, 14182, 14335, 14521, 14601, 14631, 14694, 14795, 14840, 14871, 14963, 15055, 15064, 15147, 15319, 15638, 15818, 15922, 15940, 15987, 16223, 16242, 16327, 16360, 16373, 16547, 16610, 16615, 16699, 16705, 16767, 16835, 16867, 17022, 17078, 17172, 17250, 17411, 17523, 17631, 17641, 17968, 18159, 18182, 18261, 18265, 18333, 18414, 18475, 18485, 18501, 18613, 18619, 18629, 18730, 18819, 18856, 18899, 18906, 18940, 19007, 19223, 25394, 25526, 25597, 25820, 26017, 26043, 26160, 26218, 26266, 26358, 26375, 26380, 26476, 26584, 26601, 26602, 26603, 26604, 26605, 26606, 26607, 26609, 26610, 26612, 26613, 26615, 26616, 26617, 26618, 26620, 26777, 26827, 26901, 27005, 27035, 27170, 27194, 27211, 27227, 27307, 27443, 27537, 27538, 27539, 27540, 27576, 27602, 27686, 27693, 27708, 27835, 27968, 27970, 28009, 28010, 28011, 28012, 28021, 28173, 28187, 28253, 28353, 28421, 28534, 28596, 28641, 28931, 29125, 29176, 29391, 29430, 29470, 29547, 29668, 29760, 29855, 30191, 30192, 30200, 30219, 30477, 30499, 30542, 30616, 31017, 31437, 31553, 31565, 31792, 31793, 31933, 31935, 31974, 31975, 32025, 32026, 32215, 32216, 32579, 32584, 32861, 32889, 33128, 33130, 33140, 33192, 33374, 33476, 33643, 33644, 33764, 33821, 34329, 34425, 34426, 35695, 37051, 37052, 39387, 39389, 43279
roaming config store loaded successfully - 29422 bytes.
migrating temporary roaming config store

** (steam:12597): WARNING **: replace_settings: error updating connection /org/freedesktop/NetworkManager/Settings/0 settings: (1) type

** (steam:12597): WARNING **: replace_settings: error updating connection /org/freedesktop/NetworkManager/Settings/1 settings: (1) type
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
sh: lspci: kommandot finns inte
ExecCommandLine: "/home/linus/.local/share/Steam/ubuntu12_32/steam"
System startup time: 7,73 seconds
Running Steam on   64-bit
STEAM_RUNTIME has been set by the user to: /home/linus/.local/share/Steam/ubuntu12_32/steam-runtime
Generating new string page texture 73: 1024x256, total string texture memory is 1,36 MB
Generating new string page texture 74: 256x256, total string texture memory is 262,14 KB
Generating new string page texture 75: 128x256, total string texture memory is 1,49 MB
Generating new string page texture 76: 24x256, total string texture memory is 1,52 MB
Generating new string page texture 77: 8x256, total string texture memory is 1,52 MB
Generating new string page texture 78: 32x256, total string texture memory is 1,56 MB
ExecCommandLine: "/home/linus/.steam/root/ubuntu12_32/steam steam://open/driverhelperready"
ExecSteamURL: "steam://open/driverhelperready"
Generating new string page texture 82: 64x256, total string texture memory is 1,62 MB
Generating new string page texture 83: 128x256, total string texture memory is 1,75 MB
Generating new string page texture 84: 256x256, total string texture memory is 2,02 MB
Generating new string page texture 86: 512x256, total string texture memory is 2,54 MB
Generating new string page texture 87: 128x256, total string texture memory is 2,67 MB
Generating new string page texture 88: 384x256, total string texture memory is 3,06 MB
CAPIJobRequestUserStats - Server response failed 2
Generating new string page texture 92: 128x256, total string texture memory is 3,19 MB
Generating new string page texture 95: 256x256, total string texture memory is 3,46 MB
Generating new string page texture 97: 48x256, total string texture memory is 3,51 MB
Generating new string page texture 98: 128x256, total string texture memory is 3,64 MB
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Generating new string page texture 126: 256x256, total string texture memory is 3,90 MB
saving roaming config store to 'sharedconfig.vdf'
roaming config store 2 saved successfully
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Installing breakpad exception handler for appid(steam)/version(1398287272_client)
Generating new string page texture 158: 128x256, total string texture memory is 393,22 KB
Generating new string page texture 159: 128x256, total string texture memory is 4,03 MB
Generating new string page texture 165: 64x256, total string texture memory is 4,10 MB
[2014-04-30 00:50:08] Startup - updater built Apr 23 2014 13:46:58
[2014-04-30 00:50:08] Verifierar installation...
[2014-04-30 00:50:09] Verification complete
[2014-04-30 00:51:05] Shutdown

I'm not getting a crash report though, I don't think this is a crash.

This issue is still affecting me on Xfce4 on two separate systems. One is a Thinkpad T440s, and the other is a desktop with an Asus motherboard, I forget which model.

Both systems are running Archlinux with Xfce4.

When I initiate a system shutdown using the power button, or the shutdown option in the menu, if Steam is running, it will close normally, and then nothing happens. If Steam is running, I need to attempt to shutdown, wait for Steam to close, and then attempt to shutdown again, since Steam will just cancel the first shutdown attempt.

I can confirm that this has happened to me on 5 computers since at least 5 months . 3 systems running archlinux with xfce4 , and 2 running gentoo linux also with xfce4. Only poweroffs or reboots through the terminal work the first time on all systems. Any attempt to poweroff or reboot through xfce shutdown menu force steam to close on the first attempt yet system remains up , on the second click attempt the shutdown works. Also this seems to only happen when steam is running . I have noticed this behaviour on all my computers , i am not sure if this is a steam or xfce issue.

Seeing this issue on Fedora 27 w/ KDE. This bug report is almost 4 years old at this point, are we ever going to see a fix?

Duplicate of https://github.com/ValveSoftware/steam-for-linux/issues/3301, will be tracked over there. Thanks for your patience!