Sriram reports:

On Wed, Feb 24, 2016 at 11:52 AM, Sriram Srinivasan <sriramsr@google.com> wrote:
 
I updated lulu and after that it is failing to connect to WPA network but it is able to connect fine on WEP network. I have submitted feedback as well.

Jian analyzed one log:

From the logs, shill tries to connect to the WPA network three times. All three times, the supplicant makes it all the way through (in particular, association is successful).

2016-02-24T11:49:39.127069-08:00 DEBUG wpa_supplicant[408]: wlan0: State: ASSOCIATING -> ASSOCIATED
... blablabla, then ...
2016-02-24T11:49:39.137482-08:00 DEBUG wpa_supplicant[408]: wlan0: State: GROUP_HANDSHAKE -> COMPLETED

The first attempt, shill actually manages to connect to the network (although I think this is just a race condition- nothing special about the first time).

2016-02-24T11:49:39.402266-08:00 INFO shill[592]: [INFO:service.cc(411)] Service 0: state Configuring -> Connected
2016-02-24T11:49:39.416958-08:00 INFO shill[592]: [INFO:manager.cc(1434)] Service 0 updated; state: Connected failure Unknown

But immediately afterwards, the driver times out while waiting for association (which we previously established as successful). FWIW, the signal strength at this point is -68dBm which is very weak.

2016-02-24T11:49:39.422162-08:00 ERR kernel: [  294.750847] iwlwifi 0000:01:00.0: No association and the time event is over already...
2016-02-24T11:49:39.422181-08:00 INFO kernel: [  294.750893] wlan0: Connection to AP 00:24:7b:00:00:01 lost

Consequently, we disconnect from the network.

2016-02-24T11:49:39.449084-08:00 DEBUG wpa_supplicant[408]: nl80211: Drv Event 20 (NL80211_CMD_DEL_STATION) received for wlan0
... blablabla, then ...
2016-02-24T11:49:39.463426-08:00 DEBUG wpa_supplicant[408]: wlan0: State: COMPLETED -> DISCONNECTED

Same chain of events happen in the subsequent reconnection attempts, but with the driver timing out at the configuration stage instead.