If you are facing dificulties with your internet connection and your NetworkManager isn’t running in your Ubuntu Linux system, then follow below methods to solve this problem.
Fix NetworkManager Not Running Problem on Ubuntu
1. Install and Update NetworkManager
First find whether NetworkManager Is running. In the terminal app (ctrl+alt+t) run below command.
systemctl status NetworkManager
Here the status shows as Active: active (running). If it shows as Inactive dead then you will need to install and update the NetworkManager to the latest. In the terminal run below commands one by one.
sudo apt install network-manager
sudo apt upgrade network-manager
sudo apt install network-manager-gnome
sudo apt upgrade network-manager-gnome
After that restart the NetworkManager using below command and check the internet again.
sudo systemctl restart NetworkManager
Now restart your System and check again. After the restart if the issue start again then follow below method.
2. Enable NetworkManager to Run at Startup
Open the terminal (ctrl+alt+t) and run below command.
systemctl enable NetworkManager
Now reboot your computer and then attempt to connect to the internet again. Your issue should resolve if the issue with NetworkManager was that it was unable to run at startup.