I think a lot of people have script or process to set server-id but things tend to break from time to time and it is great to get a good error message.

Server-id is stored in binary log and is integer this is why server-name would not work – too muich overhead.

Moving foward I always use a base my.cnf to I copy to any other server and the first thing is to increase the server-id.

Could MySQL just use the servername intead of a numeric value?