Signal is a great encrypted communications application built upon Electron framework. Couple of months ago I faced the issue that Signal had failed to start showing a message like this: “Uncaught Exception: Error: /tmp/.org.chromium.Chromium.j4ITUv: failed to map segment from shared object”.
After upgrade from the latest Ubuntu 16.04 LTS to Ubuntu 18.04.1 LTS, the server refused to reboot. I had to use IPMI to connect to the otherwise unresponsive server and reboot it forcefully. I probably should have used sync; reboot