Error NetworkManager is not running

The error message suggests that the NetworkManager service is not running on the system. NetworkManager is a service that manages network connections and settings on Linux-based systems.

To fix this issue, you can try restarting the NetworkManager service using the following commands:

Open a terminal window.
Check the status of the NetworkManager service by running the command:
```
systemctl status NetworkManager
```
If the service is not running, it will display an error message or status as "inactive".
Start the NetworkManager service using the command:
```
sudo systemctl start NetworkManager
```
Verify that the service is running by running the status command again:
```
systemctl status NetworkManager
```

If the service still doesn't start or if you encounter any issues, you may need to reinstall NetworkManager by running the following command:

sudo apt-get install --reinstall network-manager

After reinstalling, repeat the steps above to start the NetworkManager service.

Note: The exact commands may vary depending on your Linux distribution. The above instructions are for systems that use the systemd init system (e.g., Ubuntu, Fedora, CentOS)