Comment 32 for bug 1615474

 I also got the same error after getting a full disk message. I also played around with the WIFI access point like a previous user. I can confirm that it was enough for me to delete the file ~/.config/connectivity-service/config.ini.lock to get the network indicator back.

 It sis worth mentioning that I was able to connect via ssh, since the phone would still connect to *known* WIFI networks. I couldn't use the terminal application since it stopped working *I can use it again after the network indicator was back).