WLAN does not work. "No wireless LAN interfaces found"

[JanLahmann]

WLAN does not work. "No wireless LAN interfaces found"

[JanLahmann]

error is caused by misconfigured or non-existent file /etc/wpa_supplicant/wpa_supplicant.conf

Solution:
/etc/wpa_supplicant/wpa_supplicant.conf should contain the following entries:

country=DE
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

Resolution procedure:

• check content of /etc/wpa_supplicant/wpa_supplicant.conf
  sudo cat /etc/wpa_supplicant/wpa_supplicant.conf
• edit the file with sudo vi /etc/wpa_supplicant/wpa_supplicant.conf and add the above three lines, or issue the following command

sudo bash -c 'cat << EOF > /etc/wpa_supplicant/wpa_supplicant.conf
country=DE
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
EOF'