g_type_instance_get_private: assertion 'instance != NULL && instance->g_class != NULL' failed

[Janus]

First, my usual network disappeared from the list, and I had to connect to another. It worked great, but I needed to communicate with a machine on the old network, so I replugged my USB WLAN adapter, and I could connect again. A few minutes later, network-manager crashed. The connection still works though.

This seems to be the problem:

Sep 12 16:58:19 zeus NetworkManager[751]: (NetworkManager:751): GLib-GObject-CRITICAL **: g_type_instance_get_private: assertion 'instance != NULL && instance->g_class != NULL' failed

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: network-manager 0.9.10.0-4ubuntu15.1
ProcVersionSignature: Ubuntu 3.19.0-26.28-generic 3.19.8-ckt4
Uname: Linux 3.19.0-26-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.4
Architecture: amd64
CurrentDesktop: LXDE
Date: Sat Sep 12 17:01:51 2015
IpRoute:
 default via 192.168.2.1 dev wlan0 proto static metric 1024
 192.168.2.0/24 dev wlan0 proto kernel scope link src 192.168.2.109
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: network-manager
UpgradeStatus: Upgraded to vivid on 2015-04-19 (146 days ago)
mtime.conffile..etc.NetworkManager.NetworkManager.conf: 2015-03-16T23:56:17.808964
nmcli-con: Error: command ['nmcli', '-f', 'all', 'con'] failed with exit code 9: Error: nmcli (0.9.10.0) and NetworkManager (unknown) versions don't match. Force execution using --nocheck, but the results are unpredictable.
nmcli-dev: Error: command ['nmcli', '-f', 'all', 'dev'] failed with exit code 8: Error: NetworkManager is not running.
nmcli-nm: Error: command ['nmcli', '-f', 'all', 'nm'] failed with exit code 2: Error: Object 'nm' is unknown, try 'nmcli help'.