Wireless network connection problem in Ubuntu 15.04

When I upgrade my system from Ubuntu 14.10 to 15.04 unexpectedly my wireless connection stopped working. It shows all the available networks but cannot connect to any of them. But wired network is working fine. I googled my problem after couple of minutes this simple thing solved my problem.
Steps:

• open terminal and go to /etc/modprobe.d/
• i.e. cd /etc/modprobe.d/
• open iwlwifi.conf file in any of the text editor 
• i.e. sudo gedit iwlwifi.config
• you can see "options iwlwifi 11n_disable=8"  in the last line of the page, either comment it or delete it.
• i.e. #options iwlwifi 11n_disable=8 #this is single line comment
• re-start your system and it will works.