14.04 - Network manager stopped working
I got the same problem today.
TLDR: downgrade libnl3 or upgrade network-manager.
As per this answer, problem is that a fix in libnl3 caused a regression in network-manager. Then, it was only a bug for -proposed packages, but I guess bug was tested enough that it could be introduced into regular Ubuntu ;).
Safest way is to take a step back and install earlier versions of libnl-3-200 libnl-genl-3-200 libnl-route-3-200 (see details in said answer).
This leaves you with downgraded packages. Remember to not upgrade them until relevant upgrade for network-manager is available.
Alternatively (I did this), you can take a step ahead and install newer version of network-manager:
for amd64 or for i386. You can download package on different system and pass it with USB stick. Or download it with your smartphone and pass it via USB.
Install it with:
sudo dpkg -i network-manager_*.deb
You can try to get networking by just restarting NetworkManager:
sudo service network-manager restart
But I needed to reboot to get systray applet back.
This method works if you can connect by Ethernet cable.
Use Ubuntu's built in recovery mode to upgrade Network Manager.
Step 1
Use the down-arrow key to select Advanced options for Ubuntu and press Enter
Step 2
Use down-arrow key to select the latest Linux kernel with Recovery Mode and press Enter
I used Ubuntu, with Linux 4.2.0-36-generic (recovery mode)
Step3
Use down-arrow key to select network Enable Networking and press Enter
Step 4
Press Enter for OK to remount the file system
Step 5
Use the down-arrow key to select dpkg Repair Broken packages and press Enter
Step 6
It will ask to download the latest Network Manager with Continue [Y/n]. Input letter y for "yes" and press Enter. When all operations have finished it will say
Finished. Please press Enter
So press Enter again.
Step 7
Select resume Resume normal boot and press Enter
Step 8
Press Enter and continue to boot. At the login screen DO NOT log in instead do a NORMAL restart (click shutdown icon at the top right area of the screen).
After the PC restarts then log in.
Network connections were back when I did these steps.
You can do it this way to fix the problem:
Download file:
- libnl-3-200_3.2.21-1_XXX.deb
- libnl-route-3-200_3.2.21-1_XXX.deb
libnl-genl-3-200_3.2.21-1_XXX.deb
OS 32bit: XXX = i386 || OS 64bit: XXX = amd64
Link: http://archive.ubuntu.com/ubuntu/pool/main/libn/libnl3/
To them into one folder and install them with the command:
sudo dpkg -i lib*.deb
Then Reboot. Done :3