I had the same issue on Ubuntu 14.04 and none of proposed workarounds helped.
The way I was able to solve it was by manually restarting NetworkManager:
1) open terminal
2) type in: sudo stop network-manager
3) type in: sudo NetworkManager
And that is it! Afterwards I was able to normally connect to WiFi even after restarting Ubuntu. Hope it helps and good luck!
P.S. If restarting didnt help, before that I was also unsuccessfully trying to kill NetworkManager by its PID (it relaunches automatically), maybe it had some impact. I cant really reproduce the bug because it disappeared after restarting NetworkManager.
I had the same issue on Ubuntu 14.04 and none of proposed workarounds helped.
The way I was able to solve it was by manually restarting NetworkManager:
1) open terminal
2) type in: sudo stop network-manager
3) type in: sudo NetworkManager
And that is it! Afterwards I was able to normally connect to WiFi even after restarting Ubuntu. Hope it helps and good luck!
P.S. If restarting didnt help, before that I was also unsuccessfully trying to kill NetworkManager by its PID (it relaunches automatically), maybe it had some impact. I cant really reproduce the bug because it disappeared after restarting NetworkManager.