Mac OS 10.13.4 - can't login to messages
Updated an hour ago to the latest Mac OS 10.13.4 and am now unable to login to Messages. I can still login to my Apple ID etc. so it appears to be an issue confined to the Messages app.
iMac with Retina 5K display, macOS High Sierra (10.13.4), 32GB RAM : 1 tb SSD