I don't think this is a duplicate, anyway not one with the same cause. This started occurring after the upgrade to 15.10 beta; it wasn't an issue on 15.04.
Additionally, gdm does not even start / show the login prompt, while the original post clearly states that the user logged in first. ** This bug is no longer a duplicate of bug 1237904 Xorg crashed with SIGABRT in OsAbort() -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1502518 Title: Xorg crashed with SIGABRT in OsAbort() To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1502518/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs