I’m currently using a 15" MBP Touchbar 2017 model running 10.13.5 High Sierra. I have messages in the cloud turned on, and receive iMessage on my MBP, but am unable to send messages from my MBP. Each time I send, I get an error message. Here’s what I’ve tried so far:
Disconnect iCloud account from messages
Reconnect iCloud account from messages
I’ve also tried restarting my MBP and resetting the PRAM (not sure why, but what the heck, everyone can use a good PRAM reset every once in a while ) Any suggestions?!
Sometimes it helps to whack iCloud by logging out of it in System Preferences. Rebooting. Logging back in. This is not the last resort, but it can fix errors and mishandling. Before you log out, make sure all your settings are correct, and your accounts settings in Messages are correct. Be aware logging out of iCloud then back in again will cause a complete resync of iCloud Drive, contacts, etc.