I have same error sometimes and I have to reboot.
$ sudo prime-select nvidia Error: alternatives are not set up properly Error: nvidia mode can't be enabled
Linux 3.13.0-24-generic nvidia-prime 0.6.2 nvidia-331 331.38-0ubuntu7 Ubuntu 14.04 lightdm (1.10.0-0ubuntu3) trusty
$ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09) 01:00.0 VGA compatible controller: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/630M/720M] (rev ff)
I have same error sometimes and I have to reboot.
$ sudo prime-select nvidia
Error: alternatives are not set up properly
Error: nvidia mode can't be enabled
Linux 3.13.0-24-generic
nvidia-prime 0.6.2
nvidia-331 331.38-0ubuntu7
Ubuntu 14.04
lightdm (1.10.0-0ubuntu3) trusty
$ lspci | grep VGA 630M/720M] (rev ff)
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 VGA compatible controller: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/