I can confirm that the issue rescribed in bug #800327 is real and the workaround of adding Debian-gdm user to the video group works. The logs in this case look like this in /var/log/messages :
Sep 28 22:29:13 home gnome-session[1440]: X Error of failed request: BadValue (integer parameter out of range for operation) Sep 28 22:29:13 home gnome-session[1440]: Major opcode of failed request: 154 (GLX) Sep 28 22:29:13 home gnome-session[1440]: Minor opcode of failed request: 3 (X_GLXCreateContext) Sep 28 22:29:13 home gnome-session[1440]: Value in failed request: 0x0 Sep 28 22:29:13 home gnome-session[1440]: Serial number of failed request: 25 Sep 28 22:29:13 home gnome-session[1440]: Current serial number in output stream: 26 Sep 28 22:29:13 home gnome-session[1440]: gnome-session-check-accelerated: Helper exited with code 256 Sep 28 22:29:18 home gnome-session[1440]: X Error of failed request: BadValue (integer parameter out of range for operation) Sep 28 22:29:18 home gnome-session[1440]: Major opcode of failed request: 154 (GLX) Sep 28 22:29:18 home gnome-session[1440]: Minor opcode of failed request: 3 (X_GLXCreateContext) Sep 28 22:29:18 home gnome-session[1440]: Value in failed request: 0x0 Sep 28 22:29:18 home gnome-session[1440]: Serial number of failed request: 25 Sep 28 22:29:18 home gnome-session[1440]: Current serial number in output stream: 26 Sep 28 22:29:18 home gnome-session[1440]: gnome-session-check-accelerated: Helper exited with code 256 Sep 28 22:29:18 home gnome-session[1440]: gnome-session[1440]: WARNING: software acceleration check failed: Child process exited with code 1 However, after reviewing my upgrade log, there was no GDM upgrade, but there was a new kernel version (4.1 to 4.2.1-2) and a new NVidia driver version (340.93-1 to 340.39-2). Could this bug be instead in NVidia driver package instead? -- Best regards, Aigars Mahinovs mailto:aigar...@debian.org #--------------------------------------------------------------# | .''`. Debian GNU/Linux (http://www.debian.org) | | : :' : Latvian Open Source Assoc. (http://www.laka.lv) | | `. `' Linux Administration and Free Software Consulting | | `- (http://www.aiteki.com) | #--------------------------------------------------------------#