I have been on quite the odyssey trying to get steam to work.
I am using Ubuntu 15.04 and the linux 4.0.5 kernel. System specs:
Intel haswell quad core CPU AMD Radeon 7870 Graphics Samsung 850 EVO SSD 16GB Memory
I was able to get steam to work in 14.04LTS, but I had other problems with that version; namely flash issues in chrome. So I updated to 15.04 and my system is more stable (except for steam, there is always something...)
I have tried removing various lib files to no effect. I have removed and installed steam a few times and it doesn't appear to be working.
I tried switching to the proprietary drivers, but that causes my system to hang when it boots. In order to fix it I completely removed and purged fglrx from my system. I attempted to reinstall the proprietary drivers via command line according the ubuntu page instructions, and ran into the same error, so I am stuck with the open source drivers.
I can only assume that my card is no longer supported by the proprietary drivers, which is frustrating.
Before I removed the proprietary drivers I got the same error as these guys: https://github.com/ValveSoftware/steam-for-linux/issues/3820
Now that I have removed the proprietary drivers I am getting missing lib errors, which I guess is not surprising:
libGL error: unable to load driver: radeonsi_dri.so libGL error: driver pointer missing libGL error: failed to load driver: radeonsi libGL error: unable to load driver: swrast_dri.so libGL error: failed to load driver: swrast
I am about ready to give up and am seriously considering buying an Nvidia card. If anybody has any suggestions on what else I can do, I would really appreciate it.