Comment 2 for bug 1158706

Hi Daniel, the error in your logs indicates that separate processes that the Ubuntu One app starts are not able to connect to each other.
Has it run correctly at least once on this system?
Without knowing more context, the most likely problem here is that there is a process left over from a previous launch that is holding on to system resources (sockets, specifically) that are needed by the app when you launch it again.

I think you should be able to clear it up by quitting everything related to ubuntu one, and removing the following two directories:
~/Library/Caches/sso/
~/Library/Caches/ubuntuone/

The easiest way to quit everything is to reboot. If you don't want to reboot, you can start by quitting via the menubar icon, then look in Activity Monitor to find anything else with the name 'ubuntu' in it. Force quit those too. (You can leave the one called com.ubuntu.one.fsevents).

Please feel free to contact support if this doesn't work. You can also reply here, but contacting support will guarantee more prompt attention.