iMessage Activation Error after iOS 18.1.1 Update

issues turning on iMesssage after updating to 18.1.1 - get activation error. I have tried turingign wifi and internet on and off, and this has not resolved the issue. Why does Apple release updates with similar issues as in past updates

I go to apps and message, turn iMessage on, it goes green for a second then a pop-up saying iMessage Activation - An error occurred ruing activation. Try Again, I click OK and get the same results.

[Re-Titled by Moderator]