Every time I disconnect from a wired or wireless network using the network manager applet, I get this in
[ 2036.633608] NetworkManager: segfault at 8 ip 000000000048abc6 sp 00007ffddc984ce0 error 4 in NetworkManager[400000+2b8000]
Also the applet crashes, automatically restarts, and the network is automatically connected to again. (This makes it impossible to disconnect from a network without removing the connection or stopping network-manager manually).
The exact same thing happens on both my laptop and my desktop (they each run Ubuntu 16.04).