I upgraded my Ubuntu to 11.04 but unfortunately the X did not start anymore. I got the Login screen up, but after logging in the xserver seemed to crash and return to the login screen. After upgrading to kernel 3.0.0.13 or higher I was also unable to switch to the console mode by ctrl-alt-F7 / F6 due to non-supported screen resolution (this could be fixed by uncommenting from /etc/default/grub #GRUB_TERMINAL=console and then running sudo update-grub) . I tried a bunch of different tricks such as ones described here but without success. I was looking to the
grep ”(EE)” /var/log/Xorg.0.log
and tried to fix for example the issues with /dev/fb0 not found, drivers noveau and nv missing. However, I checked my other well functioning machine, and that had the same error messages, so they were not the cause of the problem.
Finally I also took a look in the other log files and found the problem:
Mar 27 23:29:29 server pulseaudio[1789]: [autospawn] core-util.c: Failed to create random directory /tmp/pulse-oLhPPjki4YeE: Permission denied
Mar 27 23:29:29 server pulseaudio[1789]: [autospawn] core-util.c: Failed to symlink /var/lib/lightdm/.pulse/444ae23e9ad59364ceaf30c200000006-runtime.tmp: Permission denied
The /tmp dir had too strict permissions! This was fixed quickly by:
sudo chmod a+w /tmp