Mac mini iMessage 'needs to be enabled' error
I've suddenly started getting an "iMessage needs to be enabled to send this message" on my macOS Sequoia 15.7.4 M4 Mac mini. This happened overnight: no problems yesterday, "Cannot Send Message" this morning.
Things I have tried:
• Quitting Messages.app and relaunching
• Force-quitting Messages.app and relaunching
• Restarting Mac and launching Messages
• Deleting com.apple.Messages.plist, restarting Mac and launching Messages
No dice; I'm still getting the error.
I've found lots of suggestions for dealing with this on iOS devices, but none on Macs. Please help!
Mac mini, macOS 15.7