It seems that you've edited /etc/default/grub in a way that made its syntax invalid. You need to edit it again and fix it. You can test whether you've got it right using 'sh -n /etc/default/grub', which should produce no output if the file has valid syntax.
Bug 484499 is about the fact that the upgrade crashed rather than warning you about this and giving you the opportunity to fix it.
The terminal log says:
/etc/ default/ grub: 1: splash: not found
It seems that you've edited /etc/default/grub in a way that made its syntax invalid. You need to edit it again and fix it. You can test whether you've got it right using 'sh -n /etc/default/grub', which should produce no output if the file has valid syntax.
Bug 484499 is about the fact that the upgrade crashed rather than warning you about this and giving you the opportunity to fix it.