Probably driver related. I'm running Ubuntu 16.04 64bit on an AMD processor and graphics card. Trying to run steam with LIBGL_DEBUG=verbose
gives me this:
Running Steam on ubuntu 16.04 64-bit
STEAM_RUNTIME is enabled automatically
/bin/bash: /home/grizeldi/.local/share/Steam/ubuntu12_32/steam-runtime/amd64/lib/x86_64-linux-gnu/libtinfo.so.5: no version information available (required by /bin/bash)
grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc
grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc
grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc
Installing breakpad exception handler for appid(steam)/version(1474415843)
libGL: OpenDriver: trying /usr/lib/i386-linux-gnu/dri/tls/radeonsi_dri.so
libGL: OpenDriver: trying /usr/lib/i386-linux-gnu/dri/radeonsi_dri.so
libGL: dlopen /usr/lib/i386-linux-gnu/dri/radeonsi_dri.so failed (/usr/lib/i386-linux-gnu/libLLVM-3.8.so.1: symbol _ZNKSt3_V214error_category10_M_messageB5cxx11Ei, version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference)
libGL: OpenDriver: trying ${ORIGIN}/dri/tls/radeonsi_dri.so
libGL: OpenDriver: trying ${ORIGIN}/dri/radeonsi_dri.so
libGL: dlopen ${ORIGIN}/dri/radeonsi_dri.so failed (${ORIGIN}/dri/radeonsi_dri.so: cannot open shared object file: No such file or directory)
libGL: OpenDriver: trying /usr/lib/dri/tls/radeonsi_dri.so
libGL: OpenDriver: trying /usr/lib/dri/radeonsi_dri.so
libGL: dlopen /usr/lib/dri/radeonsi_dri.so failed (/usr/lib/dri/radeonsi_dri.so: cannot open shared object file: No such file or directory)
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL: OpenDriver: trying /usr/lib/i386-linux-gnu/dri/tls/swrast_dri.so
libGL: OpenDriver: trying /usr/lib/i386-linux-gnu/dri/swrast_dri.so
libGL: dlopen /usr/lib/i386-linux-gnu/dri/swrast_dri.so failed (/usr/lib/i386-linux-gnu/libLLVM-3.8.so.1: symbol _ZNKSt3_V214error_category10_M_messageB5cxx11Ei, version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference)
libGL: OpenDriver: trying ${ORIGIN}/dri/tls/swrast_dri.so
libGL: OpenDriver: trying ${ORIGIN}/dri/swrast_dri.so
libGL: dlopen ${ORIGIN}/dri/swrast_dri.so failed (${ORIGIN}/dri/swrast_dri.so: cannot open shared object file: No such file or directory)
libGL: OpenDriver: trying /usr/lib/dri/tls/swrast_dri.so
libGL: OpenDriver: trying /usr/lib/dri/swrast_dri.so
libGL: dlopen /usr/lib/dri/swrast_dri.so failed (/usr/lib/dri/swrast_dri.so: cannot open shared object file: No such file or directory)
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast
On the same machine, on Ubuntu 15.10 32bit, steam failed to start but I solved it by removing libstdc++.so in steam runtime. I did the same on 64bit (before I got the same error than on 32bit), but now I get the error above. Help?
EDIT: This did manage to get steam up and running: Steam doesn't start after upgrade to Ubuntu 16.04