• Steam client version (build number or date): Built Aug 29 2018, 20:07:05
• Distribution (e.g. Ubuntu): Ubuntu 18.04
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Left 4 Dead 2 will not launch, the popup window says 'Preparing to launch' and then disappears. Interestingly it used to work perfectly, before one day this started. The only thing that I can think of that I did between then and now was to install the i386 architecture (my system is 64-bit). I added this architecture in order to install a game via wine. I also added a couple of other libraries: libgnutls30:i386, libldap-2.4-2:i386, libgpg-error0:i386 and ia32-libs. That's all I can find from checking my terminal logs.

I have checked the steam logs when I try and launch. Here is the output:

GameAction [AppID 550, ActionID 5] : LaunchApp changed task to ProcessingInstallScript with ""
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to SynchronizingCloud with ""
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to ProcessingShaderCache with ""
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to SiteLicenseSeatCheckout with ""
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to CreatingProcess with ""
GameAction [AppID 550, ActionID 5] : LaunchApp waiting for user response to CreatingProcess ""
GameAction [AppID 550, ActionID 5] : LaunchApp continues with user response "CreatingProcess"
Opted-in Controller Mask: 70
Game update: AppID 550 "", ProcID 3553, IP 0.0.0.0:0
>>> Adding process 3553 for game ID 550
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to WaitingGameWindow with ""
ERROR: ld.so: object '/home/tom/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/tom/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
GameAction [AppID 550, ActionID 5] : LaunchApp changed task to Completed with ""
pid 3556 != 3555, skipping destruction (fork without exec?)
ERROR: ld.so: object '/home/tom/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/home/tom/.local/share/Steam/ubuntu12_64/gameoverlayrenderer.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS64): ignored.
>>> Adding process 3554 for game ID 550
>>> Adding process 3555 for game ID 550
dbus[3558]: arguments to dbus_message_new_method_call() were incorrect, assertion "path != NULL" failed in file ../../../dbus/dbus-message.c line 1362.
This is normally a bug in some application using the D-Bus library.

  D-Bus not built with -rdynamic so unable to print a backtrace
>>> Adding process 3557 for game ID 550
>>> Adding process 3558 for game ID 550
/home/tom/.local/share/Steam/steamapps/common/Left 4 Dead 2/./hl2.sh: line 72:  3558 Aborted                 (core dumped) ${GAME_DEBUGGER} "${GAMEROOT}"/${GAMEEXE} "$@"
Game removed: AppID 550 "", ProcID 3553 
No cached sticky mapping in ActivateActionSet.