i ran into this issue on ubuntu 16.04 (64 bit), and i can confirm that both workarounds (using Nouveau and setting LD_LIBRARY_PATH=/usr/lib/nvidia-375 ) fix the issue.
to add a bit more info, it seems that in the failing case, glxinfo (or presumably the other apps), can't find the GLX_indirect library that it trys to load dynamically, which has something to glvnd: https://github.com/NVIDIA/libglvnd
looking at ldd, you can see that glxinfo is finding the GL libraries fine, using the system-set ld.so.conf settings that the nvidia driver sets up: moskewcz@mari:/etc/ld.so.conf.d$ ldd /usr/bin/glxinfo linux-vdso.so.1 => (0x00007ffe4779c000) libGL.so.1 => /usr/lib/nvidia-375/libGL.so.1 (0x00007fcd87f35000) libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007fcd87bfb000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fcd87831000) libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fcd8762d000) libGLX.so.0 => /usr/lib/nvidia-375/libGLX.so.0 (0x00007fcd873fd000) ...
the paths are set here: moskewcz@mari:/etc/ld.so.conf.d$ cat /etc/ld.so.conf.d/x86_64-linux-gnu_EGL.conf /usr/lib/nvidia-375 /usr/lib32/nvidia-375
using strace, we can see the difference that setting LD_LIBRARY_PATH makes:
# working case, opens the correct lib: moskewcz@mari:/etc/ld.so.conf.d$ LD_LIBRARY_PATH=/usr/lib/nvidia-375 strace glxinfo 2>&1 | grep GLX_ind open("/usr/lib/nvidia-375/tls/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/nvidia-375/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = 4
# non-working case, fails to open libGLX_indirect.so: moskewcz@mari:/etc/ld.so.conf.d$ strace glxinfo 2>&1 | grep GLX_ind open("/lib/x86_64-linux-gnu/tls/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/x86_64-linux-gnu/tls/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/x86_64-linux-gnu/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/x86_64-linux-gnu/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/x86_64-linux-gnu/tls/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/x86_64-linux-gnu/tls/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/x86_64-linux-gnu/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/x86_64-linux-gnu/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/tls/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/tls/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/lib/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/tls/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/tls/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) open("/usr/lib/x86_64/libGLX_indirect.so.0", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) [...snip many more repeats of failed-to-load libGLX_indirect...]
however, it's not clear why, under x2go, the nvidia code isn't searching in /usr/lib/nvidia-375 -- but it's not clear what code it uses for the DL loading, maybe it is somewhere in the glvnd code.
mwm