Not able to suspend because of Failed to connect to non-global ctrl_ifname: (nil) error: No such file or directory

Solution 1:

I found the solution. I added this line at the end of /etc/network/interfaces :

wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

And I added /etc/wpa_supplicant/wpa_supplicant.conf with this :

ctrl_interface=/var/run/wpa_supplicant
ap_scan=0
fast_reauth=0

I still cannot suspend but this is not related to this particular problem.