Ichat on Yosemite, can't log in
I just upgraded to Yosemite. Mac Pro 2010I used to be able to message from Ichat on my computer, now messages are not being sent.
When I try to log in, I get this error message. I am currently logged into iCloud and no problem with current password, just will not connect.
Thank you.
My computer shows no updates are needed.
Mac Pro (Early 2009), iOS 8.3, 10.10.3