1) Run the following command to get the "keys"
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 16126D3A3E5C1192
2) Run the above update commands again, make sure there is no error this time, and then check the update manager again.
1) Run the following command to get the "keys"
sudo apt-key adv --keyserver keyserver. ubuntu. com --recv-keys 16126D3A3E5C1192
2) Run the above update commands again, make sure there is no error this time, and then check the update manager again.