I just got this error from Kubuntu 15.x when starting up after restart to upgrade kernel.
Error getting authority: Error initializing authority: Could not connect: No such file or directory (g-io-error-quark, 1)
PS. Please note this is not a duplicate of: 'starting version 219' bug after the 15.04 update while the error message is similar, the root cause is different (which is an example of terrible design if you ask me).