Ubuntu: After 15.10 upgrade NetworkManager using 30% CPU


Just upgraded a 3rd Gen Lenovo Carbon X1 from 15.04 to 15.10 and I noticed a rise in CPU usage.

/usr/sbin/NetworkManager is using ~35% constantly and /lib/systemd/systemd-journald seems to rise when NetworkManager is started (drops when it is stopped).

Turning of the wireless adapter does nothing. Turning off bluetooth also does nothing. No LAN is connected.

Stopping the service fixes the problem, obviously, but this is not a viable option.


Turns out I had a custom config file


with one line


When I removed this file (experimenting), network manager instantly stopped using CPU and returned to normal. The problem seems to be fixed.


I had the similar problem. Another symptom was if I suspended the system, then the DNS failed to work after being awaken from suspend. What helped me was to comment out dnsmasq in /etc/NetworkManager/NetworkManager.conf.



My issue was that NetworkManager.service tried to start dnsmasq on, but that port was already taken by dnsmasq.service. The solution for me was sudo systemctl disable dnsmasq.service

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