Comment 2 for bug 1553666

i was running vagrant on ubuntu 14.04 last week, it was running perfect....but i changed OS to ubutnu 12.04 due to some personal needs, then i faced this error. I thought it may be due to old OS, i installed again ubuntu 14.04 but facing same error as ubuntu 12.04.
i have tried a lot of workarounds but no use....then i decided to report it as bug.