java.sql.SQLException: Unknown initial character set index '255' received from server for connector 8.0.11
Using MySQLWorkbench interface:
First click in your connection ->
After click in Options File
And change character-set-server and collation-server values to the values below:
Make sure to restart mysql server by opening services and restarting mysql server.
With version 8 the default characterset changed. When you add your character set to the connection URL like ?characterEncoding=latin1 it might work.
Sounds like you need to download the latest connector j jar:
http://chillyfacts.com/java-sql-sqlexception-unknown-initial-character-set-index-224-received-server/